File written by GeMS_ValidateDatabase.py, version of 11/28/2023
Tue Jun 4 09:51:35 2024
Runtime parameters
Database path: C:\Data\Pangaea\CGS\2023Wiggins\OF-23-06_Wiggins\OF-23-06_Wiggins_Publication\OF-23-06_Wiggins_Database\OF-23-06_Wiggins.gdb
Output directory: C:\Data\Pangaea\CGS\2023Wiggins\validation
Metadata file: None
Check embedded metadata: False
Skip topology check: False
Refresh GeoMaterialDict: True
Delete extra rows in Glossary and DataSources: False
Compact GDB: True

This database is LEVEL 3 COMPLIANT.

Check Metadata option was skipped. Be sure to have prepared valid metadata and check this option to produce a complete report.
This file should be accompanied by OF-23-06_Wiggins.gdb-ValidationErrors.html and a metadata summary from mp in the same directory.

If this database will be submitted to the NGMDB, it also needs to be accompanied by a reviewed Geologic Names report that includes identification of any suggested modifications to Geolex. Use the Geologic Names Check tool to generate that report or provide other documentation of a review.

Compliance Criteria
Warnings
Content not specified in GeMS schema
Occurrence of MapUnits in DMU, feature datasets, or geopackage tables
Contents of Nonspatial Tables
DataSources
DescriptionOfMapUnits
Glossary
GrainSize
MiscellaneousMapInformation
OSL
Qa3CharacteristicsTable
c14
Database Inventory

LEVEL 1

Criteria for a LEVEL 1 GeMS database are:

• No overlaps or internal gaps in map-unit polygon layer
• Contacts and faults in single feature class
• Map-unit polygon boundaries are covered by contacts and faults lines

Databases with a variety of schema may meet these criteria. This script cannot confirm LEVEL 1 compliance.

LEVEL 2--MINIMALLY COMPLIANT

A LEVEL 2 GeMS database is accompanied by a peer-reviewed Geologic Names report, including identification of suggested modifications to Geolex, and meets the following criteria:

2.1 Has required elements: nonspatial tables DataSources, DescriptionOfMapUnits, GeoMaterialDict; feature dataset GeologicMap with feature classes ContactsAndFaults and MapUnitPolys	PASS
2.2 Required fields within required elements are present and correctly defined	PASS
2.3 All MapUnitPolys and ContactsAndFaults based feature classes obey Level 2 topology rules: no internal gaps or overlaps in MapUnitPolys, boundaries of MapUnitPolys are covered by ContactsAndFaults	PASS
2.4 All map units in MapUnitPolys have entries in DescriptionOfMapUnits table	PASS
2.5 No duplicate MapUnit values in DescriptionOfMapUnit table	PASS
2.6 Certain field values within required elements have entries in Glossary table	PASS
2.7 No duplicate Term values in Glossary table	PASS
2.8 All xxxSourceID values in required elements have entries in DataSources table	PASS
2.9 No duplicate DataSources_ID values in DataSources table	PASS

LEVEL 3--FULLY COMPLIANT

A LEVEL 3 GeMS database meets these additional criteria:

3.1 Table and field definitions beyond Level 2 conform to GeMS schema	PASS
3.2 All MapUnitPolys and ContactsAndFaults based feature classes obey Level 3 topology rules: No ContactsAndFaults overlaps, self-overlaps, or self-intersections.	PASS
3.3 No missing required values	PASS
3.4 No missing terms in Glossary	PASS
3.5 No unnecessary terms in Glossary	PASS
3.6 No missing sources in DataSources	PASS
3.7 No unnecessary sources in DataSources	PASS
3.8 No map units without entries in DescriptionOfMapUnits	PASS
3.9 No unnecessary map units in DescriptionOfMapUnits	PASS
3.10 HierarchyKey values in DescriptionOfMapUnits are unique and well formed	PASS
3.11 All values of GeoMaterial are defined in GeoMaterialDict. GeoMaterialDict is as specified in the GeMS standard	PASS
3.12 No duplicate _ID values	PASS
3.13 No zero-length, whitespace-only, or bad null values	PASS

There are 32 warnings

Some of the extensions to the GeMS schema identified here may be necessary to capture geologic content and are entirely appropriate. Please document these extensions in metadata for the database, any accompanying README file, and (if applicable) any transmittal letter that accompanies the dataset. Other extensions may be intermediate datasets, fields, or files that should be deleted before distribution of the database.

Fields

CMULines, Label

Tables

CorrelationOfMapUnits
CrossSectionA
CrossSectionB
CrossSectionC
CrossSectionD
OSL
c14
GrainSize
Qa3CharacteristicsTable
GenericPoints
MapUnitPolysAnno
GeochronPointsAnno
GenericPointsAnno
CMULinesAnno
CMUMapUnitPolysAnno
CSA_DHTrace
CSAMapUnitPolysAnno
CSA_PointsAnno
CSAPoints
CSBDHTrace
CSBPoints
CSBPointsAnno
CSBMapUnitPolysAnno
CSCDHTrace
CSCPoints
CSCPointsAnno
CSCMapUnitPolysAnno
CSDDHTrace
CSDPoints
CSDPointsAnno
CSDMapUnitPolysAnno

DataSources

OBJECTID	Source	Notes	URL	DataSources_ID
9	Baylor University	None	https://geosciences.artsandsciences.baylor.edu/about-us/facilities/geoluminescence-dating-research-lab/	BAYLOR
10	Beta Analytics	None	https://www.radiocarbon.com	BETA
2	This study	None	None	DAS1
5	Online dictionary	None	https://dictionary.com/	DICT1
7	Division of Water Resources	None	https://dwr.colorado.gov/	DWR
8	Colorado Energy and Carbon Management Information System (COGIS)	None	https://ecmc.state.co.us/data.html	ECMC
1	Federal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. Geological Survey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic Data Committee Document Number FGDC-STD-013-2006, 290 p., 2 plates.	None	https://ngmdb.usgs.gov/fgdc_gds/geolsymstd.php	FGDC-STD-013-2006
3	GeMS standard	None	https://ngmdb.usgs.gov/Info/standards/GeMS/	GeMS1
4	Online geologic dictionary	None	https://geology.com/geology-dictionary.shtml	GEODICT1

DescriptionOfMapUnits

OBJECTID	MapUnit	Name	FullName	Age	Description	HierarchyKey	ParagraphStyle	Label	Symbol	AreaFillRGB	AreaFillPatternDescription	DescriptionSourceID	GeoMaterial	GeoMaterialConfidence	DescriptionOfMapUnits_ID
1	None	SURFICIAL UNITS	SURFICIAL UNITS	None	For more detail on grain size distribution, bedding, sorting, color, secondary carbonate, and other characteristics of surficial map units see Table 1a (for units Qa1, Qa2, Qes, and Qp) and Table 1b (for unit Qa3); general characteristics are presented below in the text describing the map units. For radiocarbon and optically stimulated luminescence (OSL) ages of select map units see Table 2. Subdivision of the Quaternary follows the International Chronostratigraphic Chart, v 2023/09 (International Commission on Stratigraphy, International Union of Geological Sciences, 2023). Particle size designation is according to the Udden-Wentworth grain size scale (see Nichols, 2009), but in Tables 1a and 1b on Plate 2 the designation is modified such that sand-size categories are divided into coarser (U) and finer (L) sub-categories with the aid of a sand grain-size card (US GeoSupply, Incorporated, 2020). For example, very coarse (vc) sand is divided into the categories vcU (very coarse upper – coarser) and vcL (very coarse lower – finer). In this report the term “fines” refers to silt- and clay-sized particles. The term “clay” refers to clay-rich sediments. In Tables 1a and 1b the colors are designated with the aid of color charts of Munsell Color (1991) and Visual Color Systems (no publication date). Description of soil calcium carbonate (CaCO3) morphology is after Machette (1985), and the type of effervescence in sediment or soil observed when treated with dilute hydrochloric acid is according to U.S. Department of Agriculture (2018).	01	DMUHeading1	None	None	None	None	DAS1	None	None	DMU01
3	None	HUMAN-MADE DEPOSITS	HUMAN-MADE DEPOSITS	None	None	01-01	DMUHeading2	None	None	None	None	DAS1	None	None	DMU02
4	af	Artificial Fill	Artificial Fill	Upper Holocene	Mostly riprap, fill material, and material placed during construction of roads, railroads, buildings, stockyards, dams, storage ponds, and landfills. The fill deposits generally consist of unsorted clay, silt, sand, and rock fragments. Typically, the unit is less than 6 m thick. Some deposits of artificial fill (e.g., state highways and county roads) are not mapped because they are too narrow for presentation at map scale. Artificial fill may be subject to settlement, slumping, and erosion if not adequately compacted and(or) if placed on unstable slopes.	01-01-01	DMUUnit1	af	af	255,255,255	None	DAS1	"Made" or human-engineered land	High	DMU03
21	sand pit	sand pit	sand pit	Holocene	None	01-01-02	DMUUnit1	sand pit	sand pit	None	None	None	"Made" or human-engineered land	High	DMU04
5	None	ALLUVIAL DEPOSITS	ALLUVIAL DEPOSITS	None	None	01-02	DMUHeading2	None	None	None	None	DAS1	None	None	DMU05
6	Qa1	Alluvium one	Alluvium one	Upper Holocene	Unit Qa1, also known as post-Piney Creek Alluvium, occupies active and historically active channels of Bijou Creek, Antelope Creek, and Kiowa Creek. According to local landowners contacted during the summer 2022 field work for this map, Kiowa Creek flooded during 2013 and Antelope Creek last flowed during 2015. All three creeks were dry when observed during field work in 2022. Reports from locals and new sand deposits observed in 2023 indicate that the main channel of Bijou Creek was active during the summer of 2023. The Bijou Creek unit Qa1 channel is much wider than its tributary, the Antelope Creek unit Qa1 channel, and much wider than the Kiowa Creek unit Qa1 channel. Lidar imagery of unit Qa1 in the Bijou Creek valley shows a network of braided historical channels and channel bars, including the present active channel. The full thickness of unit Qa1 was not exposed but may be 2 m or less. Most of unit Qa1 is weakly cohesive to loose pinkish-white and light-gray sand. The sand is fine to coarse or is medium to coarse with rare very coarse grains. Rare gravel content ranges in size from granules to pebbles as large as 10 mm. Locally, coarse sand interbeds 6–10 cm thick are present in the unit. Sand composition is estimated as 85–90% quartz, 5–14% feldspar, and from <1 to 5% opaques, with trace mica. Gravel content is granitic. In Antelope Creek there are some muddy reaches ~2–3 meters long that have prominent desiccation cracks; these possibly are overbank deposits. No secondary carbonate was observed in this unit.	01-02-01	DMUUnit1	Qa1	Qa1	254,246,136	156,156,156 ESRI geology 24k 601 Gravel, open	DAS1	Alluvial sediment, mostly coarse-grained	High	DMU06
7	Qa2	Alluvium two	Alluvium two	Upper to Middle Holocene	Unit Qa2, also known as Piney Creek Alluvium (Scott, 1960), occupies a large portion of the Bijou Creek valley, occurring 1 to 2 m above both sides of unit Qa1 (the area of active and historic channels) and forming the lowest terrace of the valley. In the Bijou Creek valley the unit Qa2 fill terrace is ~3 to 6 m below the fill-cut terraces of unit Qa3 that bound unit Qa2 on both sides. In the Kiowa Creek valley unit Qa2 forms two small fill terraces, ~ 1 to 2 m lower than the Qa3 fill terrace of that valley (the valley has no fill-cut terraces in unit Qa3). Lidar imagery of the Bijou Creek valley shows that braided channels of unit Qa2 are approximately twice as wide as those of the unit Qa1 channels, and that the unit Qa2 channel bars are more numerous and much larger than those of unit Qa1. The different surface characteristics of the two units, although observable in the field, are more prominent in lidar imagery and allow the units to be readily distinguished for mapping purposes. Also, in lidar imagery of the Bijou Creek valley, the relatively rough surface morphology of unit Qa2 with its many braided channels and bars contrasts markedly with the higher, relatively smoother surface of the bounding unit Qa3 terraces (although the latter have a few prominent channel bars). Unit Qa2 is incised into unit Qa3 and neither the base nor the total thickness of unit Qa2 is exposed. Thickness is estimated to be 7–8 m based upon the limited water well data for unit Qa2 in the Wiggins quadrangle. At most locations unit Qa2 consists of light-gray to light-brown sand with fines (particles < 2 mm in diameter) being absent or minor. The sediment is very fine to fine sand with rare medium sand; and fine to medium or coarse sand with minor very fine sand, and some rare coarse or very coarse sand, and granules up to 3 mm. At one location (along Kiowa Creek) unit Qa2 is a very well-sorted, very fine sand with trace fine mica, interbedded with dark-gray clay layers 6–7 cm thick and lighter-colored silty layers 2–3 cm thick. At a few locations in the Bijou Creek valley unit Qa2 consists of light to dark grayish-brown sandy clayey silt or sandy silty clay, with 30–50% sand content consisting of very fine sand, or of very fine to coarse sand with rare very coarse sand. At most locations unit Qa2 contains no secondary carbonate. At one location (in Kiowa Creek), the sandy clayey silty or sandy silty clay contains a few very small carbonate nodules having violent effervescence. At a few locations the matrix has strong effervescence, but nodules are not present. The coarser sand beds of unit Qa2 have no secondary carbonate. Radiocarbon sample WS099C14, from unit Qa2 clay exposed along Kiowa Creek (location labeled on geologic map), yielded a conventional radiocarbon age of 4,420±30 yr (Middle Holocene) (Table 2). OSL sample WS105OSL, from unit Qa2 sand exposed along Bijou Creek, yielded an age of 1,095±135 yr (Late Holocene) (Table 2). Post-Piney Creek alluvium (unit Qa2) is estimated by Kellogg and others (2008) to be as old as ~4 ky. Colorado Geological Survey (CGS) radiocarbon ages for unit Qa2 and unit Qa (Quaternary alluvium, undivided; time-equivalent to unit Qa2) in other quadrangles in the northern Colorado Piedmont are approximately 1.3–4.6 ky (Madole, 2016; Keller and Morgan, 2018; Palkovic and others, 2018; Keller and others, 2019; Palkovic and others, 2019; Keller and Morgan, 2020; Lindsey and Palkovic, 2020; Palkovic and Morgan, 2021; Keller and Marr, 2023a; Keller and Marr, 2023b). Unit Qa2 in the Wiggins quadrangle is unlikely to be a potential source of aggregate because the deposit contains very little gravel and has a large fines fraction. Areas mapped as Qa2 are prone to periodic flooding.	01-02-02	DMUUnit1	Qa2	Qa2	254,246,136	215,176,158 ESRI geology 24k 601 Gravel, open	DAS1	Alluvial sediment, mostly fine-grained	High	DMU07
8	Qa3	Alluvium three	Alluvium three	Middle Holocene to Upper Pleistocene	Unit Qa3 is also known as Broadway Alluvium (Scott, 1960) and has been mapped in nearby areas by Lindsay and others (2005) and by Berry and others (2019). In the Orchard quadrangle, adjoining the Wiggins quadrangle on the north, unit Qa3 is mapped as sidestream deposits (Qbs) of Broadway Alluvium (Berry and others, 2015a, 2019). This is a subdivision of Broadway Alluvium including Late Pleistocene deposits of major north-flowing tributaries to the South Platte River (Berry and others, 2015a). CGS unit Qa3 in the Wiggins quadrangle is continuous with and equivalent to unit Qbs in the Orchard quadrangle. According to Madole (1991), Broadway Alluvium near the Front Range consists of vertical sequences of superposed, longitudinal bars of sand and gravel deposited by braided streams flowing eastward from the Front Range. These sequences locally contain finer-grained layers that probably are overbank deposits. Unit Qa3 covers more than half of the Wiggins quadrangle, including the valleys of Bijou Creek, Antelope Creek, and Kiowa Creek, and the paleovalleys of the (informally named) County Road 3 and Empire Reservoir paleovalleys (see geologic map). The deposit overlies Pierre Shale, underlies valley alluvium of units Qa2 and Qa1, and underlies eolian sand (unit Qes) of a dune field between the Kiowa Creek and Bijou Creek valleys. Unit Qa3 is syndepositional with the eolian deposits and overlaps the dune field. Eolian deposition began in Late Pleistocene time on a lower-elevation aggradation surface of unit Qa3 in both valleys, and as the alluvium aggraded it partially buried the dune field. This is indicated by interpretation of lidar imagery and by the optically stimulated luminescence (OSL) age of ~13 ky (Late Pleistocene) for the dune field covering the upland east of the Bijou Creek valley (location WS111OSL, geologic map). This upland is at about the same elevation as the dune field between the two creeks, suggesting that the two dune fields are about the same age. Ages of unit Qa3 in the Kiowa Creek and Bijou Creek valleys are ~10 ky (WS059OSL) and ~6 ky (WS025OSL) (see geologic map for locations), younger than the age of the dune field between them (providing that the dune field is about the same age as unit Qes in the upland east of Bijou Creek). Detailed plotting of sediments from water well logs in Wiggins quadrangle (Colorado Division of Water Resources, 2022) was the basis for the Plate 2 cross sections. The data analyses indicate that unit Qa3 is generally dominated by sand, with subordinate clay layers, in its upper ~20 m; and dominated by gravel and sand layers, with subordinate clay layers, from a depth of ~20 m down to bedrock. Unit Qa3 underlies the dune field between the two creeks, and this supports the hypothesis that the lower portion of the dune field was deposited on the unit Qa3 valley floor during the Late Pleistocene. Sand content of unit Qa3 is generally 85–90% quartz, 10–14% feldspar, <1% opaques, with trace mica. Unit Qa3 thickness ranges approximately from 17–67 m, with the greatest thickness being in the Bijou Creek valley (cross sections B-B’, C-C’, and D-D’, Plate 2). Unit Qa3 has a variable thickness because of the topography of the Pierre Shale surface beneath it. Descriptions of unit Qa3 in each of the above five drainages follow. Unit Qa3 in the Bijou Creek valley consists of three different types of sand. 1) The first type is a medium to coarse sand occurring on the east valley terrace, 2 km south of City of Fort Morgan water treatment plant (near sample location WS111OSL shown on the geologic map); in the northeast quadrant of the quadrangle; and on the valley’s west terraces between County Roads O and Q. It contains a small fraction of very fine to fine sand, rare granules and small pebbles, and 0–25% fines. The sediment has layers of gravelly (granules and small pebbles) sand; fine to medium sand containing some coarse to very coarse sand; medium sand to granules and pebbles; and sandy clayey silt. 2) The second type, a very fine to medium sand, occurs on the valley’s east terraces, 2 km south of the water treatment plant, and occurs in uplands between Bijou Creek and Antelope Creek near the quadrangle south boundary. 3) The third type, a clayey silty sand, covers the valley’s west terraces between County Roads L and Q. Generally, the sand fraction of unit Qa3 is mostly fine to coarse sand with minor very fine and very coarse sand and minor granules and pebbles; the fines content is 15–40%. Unit Qa3 colors in the Bijou Creek valley are light yellowish brown, dark brown, dark grayish brown, and light olive brown. Sand content is 85–90% quartz, 10–14% feldspar, <1% opaques, with trace mica. Generally, unit Qa3 becomes finer grained in the downstream direction (northward) in the Bijou Creek valley. OSL sample WS059OSL was collected from the unit Qa3 fill terrace in the Kiowa Creek valley (see geologic map for locations) and yielded an age of 9,810±440 yr (Early Holocene). OSL sample WS025OSL was collected from a unit Qa3 fill-cut terrace ~3 km east of the town of Wiggins and yielded an age of 6,125±255 yr (Middle Holocene). OSL sample WS103OSL was collected from unit Qa3 in a fill-cut terrace on the west side of Bijou Creek and yielded an age of 910±30 yr. Because this sample was taken from unit Qa3, much of which is known to be of Late Pleistocene age, this laboratory age is in error possibly due to sample contamination or exposure to light. (For complete laboratory age results see Table 2, Plate 2.) Unit Qa3 alluvium of the Antelope Creek valley consists of three types of sediment. 1) The first type is very fine to medium sand, with rare coarse to very coarse sand and rare granules and pebbles. Fines usually are absent, but one location has a 10% fines fraction. 2) The second type is dominated by clayey silty sand, with the sand fraction mostly fine to coarse with minor very fine sand; there is subordinate coarse to very coarse sand with rare granules and pebbles; and minor very fine to medium sand with minor coarse to very coarse sand having rare granules and pebbles, and a fines fraction of 10–25%. 3) The third type is sandy silty clay (60-80% fines) with the sand fraction varying from very fine to fine, to very fine to medium with rare coarse sand and granules. Unit Qa3 colors in the Antelope Creek valley are brown, dark grayish brown, light olive brown, and yellowish brown. Unit Qa3 sediment in the Antelope Creek valley is generally finer than that of the Bijou Creek valley, to which Antelope Creek valley is a tributary. Unit Qa3 alluvium of the Kiowa Creek valley consists of three types of sediment. 1) The first type is fine to medium sand occurring downstream (northward) from Wiggins. It contains rare coarse sand to granules, fine to coarse sand with minor very fine sand and minor fines, and rare very coarse sand and granitic granules and pebbles. 2) The second type is clayey silty sand, in the part of the valley from the Omar quadrangle (adjacent to the west of the Wiggins quadrangle) downstream approximately to Wiggins. The sand fraction is locally a medium to coarse sand with subordinate very fine to fine sand and rare very coarse sand and granules; and locally a very fine to medium sand with rare coarse to very coarse sand. The fines fraction of the second type is 10–30%. 3) The third type is silty clay and sandy clayey silt, occurring in the part of the valley between Wiggins and the west quadrangle boundary. The sand is very fine to medium with rare coarse sand and granules, and the fines fraction is 15–40%. Unit Qa3 colors in the Kiowa Creek valley are pale brown, brown, grayish brown, light gray, and dark gray.	01-02-03	DMUUnit1	Qa3	Qa3	255,255,115	76,230,0 ESRI geology 24k 601 Gravel, open	DAS1	Alluvial sediment, mostly fine-grained	High	DMU08
9	None	EOLIAN, POND, AND SHEETWASH DEPOSITS	EOLIAN, POND, AND SHEETWASH DEPOSITS	None	None	01-03	DMUHeading2	None	None	None	None	DAS1	None	None	DMU09
10	Qes	Eolian sand	Eolian sand	Upper Pleistocene	Unit Qes covers approximately one-quarter of the Wiggins quadrangle, including the extensive body of eolian sand occupying the upland between the Kiowa Creek and Bijou Creek valleys and extending south between the Bijou Creek valley and the County Road 3 drainage; the uplands in the northwest and southwest corners of the quadrangle; and the upland on the east side of the quadrangle. Eolian sand in the quadrangle is part of the eastern South Platte sand area, as mapped by Madole and others (2005). This sand body is one of several extensive, eastern Colorado eolian sand deposits mapped and described in that publication. Eastern Colorado dunes range in form from sand sheets to parabolic dunes, the latter being the dominant form in northeastern and central Colorado (Madole and others, 2005). In the Wiggins quadrangle, areas covered by unit Qes consist of mostly stable, vegetated, parabolic sand dunes paired with abundant blowouts. The many superposed dune crests combined with the bowl-shaped blowouts (zones of sand deflation) create the dune form known as compound parabolic dunes (Madole and others, 2005). These dunes are typical of unidirectional paleowind direction (generally from the northwest in the Wiggins quadrangle). Lidar imagery of the Wiggins quadrangle shows eolian sand terrain as distinctly characterized by dunes trending north-northwest to south-southeast, by blowouts whose long directions are parallel to the dunes, and by flat, elongate interdunal areas containing pond and sheetwash sediments of unit Qp (discussed further on in this section). Cross sections B-B’, C-C’, and D-D’ (Plate 2) are based on water well data and lidar imagery and show unit Qes to overlie and be partially overlain by alluvium of unit Qa3. Unit Qes thickness varies between 3 and 20 m. Unit Qes is readily recognized in road cuts and in sample holes dug deeper than its thin and poorly developed soil A horizon (generally less than 20 cm thick). (For definitions of soil horizons see Birkeland, 1999.) Unit Qes typically is composed of yellowish-brown to olive brown fine to medium sand, with minor very fine sand and rare coarse to very coarse sand. In a few places the sediment is very fine to fine sand with rare medium sand; or medium to coarse sand, having minor very fine to fine sand and rare very coarse sand. Rare gravel content consists of granules up to 3 mm. Sand composition is 80–95% quartz, 4–17% feldspar, and <1–5% opaques, with trace mica up to 2 mm in diameter. At some locations the deposit has planar bedding at a scale of 1–20 cm and the beds are distinguishable by differences in grain size. Unit Qes ranges from loose to moderately cohesive, depending on moisture content and very fine sand content, though it is typically weakly cohesive. Platy partings are present in some of the more consolidated deposits. Scattered carbonate filaments and nodules of secondary carbonate were observed only on the east bluff of the Bijou Creek valley near sample location WS111OSL. Optically stimulated luminescence (OSL) sample WS110OSL, collected from unit Qes exposed on the east bluff of the Bijou Creek valley (geologic map), yielded an age of 12,755±615 yr (Late Pleistocene) (Table 2). Madole and others (2005) collected a radiocarbon sample from a buried soil in the uppermost part of the eolian sand near Wiggins and obtained an age of ~9.5 ky. This suggests a possible Late Pleistocene age for the eolian sand upon which the soil was formed. The above CGS OSL age of ~12.8 ky indicates that the lower part of unit Qes in the Wiggins quadrangle is Late Pleistocene. Late Pleistocene sand is the oldest of three age groups designated for eastern Colorado eolian sand (Madole and others, 2005). There is an abundant, relatively clean sand resource in unit Qes in the Wiggins quadrangle.	01-03-01	DMUUnit1	Qes	Qes	255,247,153	None	DAS1	Dune sand	High	DMU10
11	Qp	Pond and sheetwash deposits, undivided	Pond and sheetwash deposits, undivided	Middle Holocene	Unit Qp accumulated in relatively flat, elongate depressions within dune fields of unit Qes, and in parts of the Kiowa Creek valley that formerly may have been temporarily dammed wetlands or may have been partially enclosed by sand dunes. The long axes of the enclosed interdune depressions are generally parallel to the trend of the surrounding linear dunes, and the depressions are lower in elevation than the floors of nearby Kiowa Creek and Bijou Creek valleys. The largest enclosed deposit of unit Qp is ~1,100 m long and ~360 m wide. Unit Qp deposits are indicated by enclosures within topographic contours, are recognizable in the field, and are distinct on lidar imagery. In the Wiggins quadrangle only three water wells are in deposits of unit Qp, and only one penetrates the unit entirely. The geologic log for this well indicates a 6-m-thick layer of clay with some sand content (unit Qp), overlying a layer of gravel, sand, and clay (alluvium of unit Qa3). In cross sections B-B’, C-C’, and D-D’ (Plate 2) unit Qp is interpreted as ranging between 2 and 6 m in thickness. At most locations unit Qp is composed of light to dark grayish-brown or light- to medium-brown silty clayey sand or clayey silty sand, with a fines content of 10–40%. The sediment is dominantly very fine to fine or medium sand with rare coarse to very coarse sand. Locally the deposit is a fine to a medium or coarse sand, with minor very fine sand and rare coarse sand having granules up to 3 mm; or a medium to coarse sand with minor very fine to fine sand and rare coarse to very coarse sand. Unit Qp is well exposed only in two places, at ~1.6 km and 3.2 km south of the town of Wiggins. At different levels of these exposures the bedding is on the order of millimeters, 1 to 3 cm, or there is no discernable bedding. At one of the exposures there is marked soft-sediment deformation (described further on in this section). More sandy portions of unit Qp probably are sheetwash deposits originating from the surrounding dunes. The sand fraction of the silty clayey sand or clayey silty sand is 85–90% quartz, 4–14% feldspar, <1–5% opaques, with (at many locations) trace mica. The rare granules are granitic. The dominance of fines in this sediment suggests a minor episode of loess deposition in ephemeral interdunal ponds. Radiocarbon sample WS137BC14, collected from pond sediments in an enclosed depression in the upland south of the town of Wiggins, yielded a conventional age of 6,110±30 yr. (See Table 2 on Plate 2 for details on sample ages.) A distinctive, dark-gray clay or clayey silt layer up to 3 m thick (in excavations), underlying <1 m of alluvial sand, was observed south of the town of Wiggins and on the east side of the Kiowa Creek valley, and a similar layer was observed in an excavation in the Omar quadrangle, in the Kiowa Creek valley and ~3 km west of the Wiggins quadrangle west boundary. The conventional radiocarbon age for this clay near Wiggins is 4,090±30 yr (sample WS096C14) and the radiocarbon age in the Omar quadrangle is 3,420±30 yr (sample WS060C142); both ages are Middle Holocene. This clay could have been deposited in flood-plain areas that temporarily were partially dammed by dunes. Unit Qp can be bedded or massive and at some locations it has platy partings and laminations. Some of the sediment weathers into blocky fragments. Very rarely the sand fraction is found concentrated in small masses up to 10 mm in diameter, and locally there are striations on polished surfaces of the deposit. The striations suggest alternating shrinking and swelling of the material. Unit Qp is most commonly cohesive. At some locations no secondary calcium carbonate is apparent. At other locations, however, carbonate filaments 1–2 mm thick and up to 10 mm long and(or) nodules up to 15 mm are present. Where present, the filaments range from 3–10% of the mass and nodules can be up to 20–25% of the mass. Filaments and nodules typically effervesce violently, whereas the surrounding mass effervesces weakly to moderately. In locations with significant amounts of calcium carbonate, secondary calcium carbonate may fill fissures in the sediment. Soft-sediment deformation in unit Qp is well expressed at two exposures where the contacts between pond and sheetwash deposits and the surrounding eolian sand are distinct. At one exposure there are many tube-shaped structures consisting of unit Qes eolian sand extending upward into the overlying Qp unit deposits. The sand structures range from 4–7 cm in diameter and 12–60 cm long, are spaced less than 0.5 m apart, terminate upward in the eolian sand, and have rounded tops. From observing the three-dimensional exposure of the structures, and the casts remaining after erosion of the exposure, the structures are seen to connect only with the underlying eolian sand layer and do not extend to either the top of unit Qp or the ground surface. Thus, the tube-shaped structures apparently are not animal burrows but possibly resulted from liquefaction and injection of eolian sand upward into the overlying pond and sheetwash deposits. At another exposure, a layer of unit Qp apparently was detached and slumped into unit Qes sediments. The layer is ~0.25 m thick and 3 m long, is overlain and underlain by unit Qes sand, and has marked plastic deformation. Below this apparently detached layer is a layer ~1 m thick, which consists of a matrix of eolian sand that contains fragments of unit Qp deposits. A possible explanation for these soft-sediment deformation features is that sediment gravity flow, from the flank of an adjacent sand dune, resulted in rapid sediment loading and associated lateral stresses and elevated pore pressures in saturated or nearly saturated sediments in units Qp and Qes. Unit Qp is not a suitable sand resource because of its high fines content. Unit Qp may exhibit swelling soil characteristics if the fine content contains expansive-clay minerals.	01-03-02	DMUUnit1	Qp	Qp	230,230,0	None	DAS1	Lacustrine sediment, mostly fine-grained	High	DMU11
12	None	BEDROCK GEOLOGY	BEDROCK GEOLOGY	None	Within the Wiggins quadrangle the only bedrock unit mapped at the ground surface is the Pierre Shale, interpreted to be the Upper Transition Member because it underlies the Fox Hills Sandstone (Scott, 1978). The only exposure of this unit is along a bluff on the east side of the Bijou Creek valley, near the City of Fort Morgan water treatment plant in the northeast portion of the quadrangle. In cross section A-A’ the Pierre Shale is undivided. Scott (1978), in his geologic map of the Sterling 1° x 2° quadrangle, does not give a thickness for the Upper Transition Member and the oil and gas well records for the Wiggins quadrangle have no formation picks for Pierre Shale members. The description of the Upper Transition Member is modified from Scott (1978), and for more detail on the Pierre Shale in northeast Colorado see Scott and Cobban (1965) and Braddock and others (1988). The description and regional thickness of the Fox Hills Sandstone are from Scott (1978) and Spencer (1986), and its thickness in cross section A-A’ is interpreted from Deschesne and others (2011). Note that units below the Pierre Shale are shown in cross section only. In cross section A-A’ the descriptions of units below the Pierre Shale are adapted from descriptions in the geologic map of the Carter Lake Reservoir quadrangle, ~90 km to the west of the Wiggins quadrangle, where these older units are described in outcrop (Braddock and others, 1988). Thickness values for the Pierre Shale and older units shown in cross section A-A' were calculated from oil and gas well records from the Colorado Energy and Carbon Management Commission (ECMC) (2023).	02	DMUHeading1	None	None	None	None	DAS1	None	None	DMU12
14	Kfh	Fox Hills Sandstone	Fox Hills Sandstone	Upper Cretaceous	Fine- to coarse-grained, yellowish-brown to yellowish-gray to white, quartzose sandstone; cross bedded in the lower part, grading upward to a massive, fine- to medium-grained sandstone. The unit contains some thin beds of olive-gray sandy shale and gray to brown, hard, calcareous sandstone concretions as large as 2.4 m in diameter. Regional thickness ranges from 46 to 91 m. In the southeast corner of the Wiggins quadrangle, the Fox Hills Sandstone overlies the Pierre Shale and is covered by eolian sand of unit Qes. From Colorado Geological Survey archive data used in preparation of Dechesne and others (2011), thickness is interpreted to be ~30 m at the quadrangle’s west boundary; unit pinches out ~1 km east of the boundary (cross section A-A’).	02-01	DMUUnit1	Kfh	Kfh	None	None	DAS1	Sandstone	High	DMU13
15	Kp	Pierre Shale, Upper Transition Member	Pierre Shale, Upper Transition Member	Cretaceous	Marine strata composed of dark-gray shale, siltstone, and fine-grained sandstone. Bentonite beds, rich in weathered volcanic ash, are common in the lower part and calcareous concretions are common throughout. The various members of the Pierre Shale contain index fossil ammonite species (Scott and Cobban, 1965). The Upper Transition Member, the only part of the Pierre Shale exposed in the Wiggins quadrangle, occupies the lower part of the bluff along the east side of the Bijou Creek valley in the northeast corner of the quadrangle. Regionally, the Upper Transition Member is a dark-gray, calcareous silty shale or claystone, shaly sandstone, and sandy shale. It is a marine formation that contains fossil ammonites and baculites (both are cephalopods), calcareous concretions up to 1.8 m in diameter, limestone beds as great as 1 m thick, and thin gypsum layers. The overall regional thickness of the Pierre Shale, including all its members, is ~1,650 m (see cross section A-A', Plate 2). At the Bijou Creek valley bluff, the vertical exposure of the Upper Transition Member is less than 2 m. There, the unit is a yellowish-brown to very pale-brown, moderately sorted, very fine-grained to fine-grained shaly sandstone with a fines content of up to 20%. The sandstone is weakly indurated, breaks along bedding planes, and is bedded at a scale from laminae (<0.5 mm) to ~2 cm. Bedding is indistinct at the weathered exposure but distinct where the exposure is excavated. There are rare black fragments, likely plant remains, that have stemlike forms and are pressed flat along some of the bedding planes; the fragments are ~0.5 mm wide, and ~6 mm long. The sandstone has subvertical joints which cause it to break in a blocky manner. The joints have secondary calcium carbonate coatings and filaments, the latter being up to 1 mm thick and several centimeters long.	02-02	DMUUnit1	Kp	Kp	None	None	DAS1	Mostly mudstone	High	DMU14
16	Kn	Niobrara Formation, undivided, shown in cross section only	Niobrara Formation, undivided, shown in cross section only	Upper Cretaceous	Dark-gray, very fissile, shale containing thin (5 m) micritic limestone layers. Unit is an important oil and gas resource in much of the Denver Basin, but not in the Wiggins quadrangle according to ECMC (2023) data (see section on Mineral Resources, Groundwater Resources, and Geologic Hazards, Plate 2). Thickness is 90–105 m.	02-03	DMUUnit1	Kn	Kn	None	None	DAS1	Mostly mudstone	High	DMU15
17	Kcgg	Colorado Group — Carlile Shale, Greenhorn Limestone, Graneros Shale, and Mowry Shale (undivided), shown in cross section only	Colorado Group — Carlile Shale, Greenhorn Limestone, Graneros Shale, and Mowry Shale (undivided), shown in cross section only	Upper Cretaceous	Olive-gray silty claystone and sandy claystone; dark-gray limestone and olive-gray, calcareous, silty claystone and siltstone; dark-gray to grayish-black siltstone and claystone and siliceous shale. Combined thickness is 115–120 m.	02-04	DMUUnit1	Kcgg	Kcgg	None	None	DAS1	Mostly mudstone	High	DMU16
18	Kd	Dakota Group — South Platte Formation and Lytle Formation, undivided, shown in cross section only	Dakota Group — South Platte Formation and Lytle Formation, undivided, shown in cross section only	Lower Cretaceous	Unit consists of gray to light-brown, well-sorted, fine- to medium-grained sandstone; dark-gray carbonaceous shale; gray to light-brown, fine-grained sandstone; and gray to light-brown, coarse-grained, conglomeratic sandstone. Combined thickness is 155 m.	02-05	DMUUnit1	Kd	Kd	None	None	DAS1	Sandstone	High	DMU17
19	Q	Quaternary sediments	Quaternary sediments	Upper Holocene to Upper Pleistocene	Quaternary units, undivided	03	DMUUnit1	Q	Q	None	None	None	Alluvial sediment	High	DMU18
20	water	water	water	Holocene	None	04	DMUUnit1	water	water	None	None	None	Water or ice	High	DMU19

Glossary

OBJECTID	Term	Definition	DefinitionSourceID	Glossary_ID
23	1 SD	A statistic used as a measure of the dispersion or variation in a distribution or set of data, equal to the square root of the arithmetic mean of the squares of the deviations from the arithmetic mean.	DICT1	GLO01
12	Age	the length of time during which a being or thing has existed; length of life or existence to the time spoken of or referred to	DICT1	GLO02
19	Bedrock	A graphic representation of the intersection of the geological bodies in the subsurface with a vertical plane of a certain orientation showing relationships in the bedrock	DAS1	GLO03
4	boundary	A line that marks the limits of an area	DICT1	GLO04
16	C14	Carbon-14, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues to date archaeological, geological and hydrogeological samples	GEODICT1	GLO05
1	certain	Identity of a feature can be determined using relevant observations and scientific judgment; therefore, one can be reasonably confident in the credibility of this interpretation.	FGDC-STD-013-2006	GLO06
3	contact	A geological contact is a boundary which separates one rock body from another. A contact can be formed during deposition, by the intrusion of magma, or through faulting or other deformation of rock beds that brings distinct rock bodies into contact.	GEODICT1	GLO07
14	Deposit type	Groupings for surficial units in the CMU	DICT1	GLO08
5	DMUHeading1	GeMS hierarchy formatting term	GeMS1	GLO09
6	DMUHeading2	GeMS hierarchy formatting term	GeMS1	GLO10
7	DMUUnit1	GeMS hierarchy formatting term	GeMS1	GLO11
10	ElevTick	A hatch mark shown on the edges of geologic cross sections to denote the elevation	DICT1	GLO12
17	Feature	The term can be defined as any physical feature of the earth's surface	DICT1	GLO13
8	frame	A border enclosing the cross section data	DICT1	GLO14
24	High	unusual or considerable in degree, power, intensity, etc.	DICT1	GLO23
15	O&G well	An oil well is a boring in the Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may be termed a gas well.	ECMC	GLO15
13	OSL	Optically-Stimulated Luminescence is a late Quaternary dating technique used to date the last time quartz sediment was exposed to light. As sediment is transported by wind, water, or ice, it is exposed to sunlight and zeroed of any previous luminescence signal.	GEODICT1	GLO16
20	Quaternary	A graphic representation of the intersection of the geological bodies in the subsurface with a vertical plane of a certain orientation showing relationships in the Quaternary units	DAS1	GLO17
25	questionable	Identity of a feature cannot be determined using relevant observations and scientific judgment; therefore, one cannot be reasonably confident in the credibility of this interpretation. For example, IdentityConfidence = questionable is appropriate when a geologist reasons "I can see some kind of planar feature that separates map units in this outcrop, but I cannot be certain if it is a contact or a fault."	FGDC-STD-013-2006	GLO24
22	radiocarbon BP	The conventional radiocarbon age in years BP (before present) reflects the concentration of radiocarbon in a sample (with 0 BP defined as the radiocarbon concentration in AD 1950).	GEODICT1	GLO18
9	surface	The topographic profile of the cross section	DICT1	GLO19
18	Water feature	The term can be defined as any physical water feature of the earth's surface	DICT1	GLO20
11	Water well	Wells (bore holes) that penetrate artesian aquifers. Water will rise up the well casing to the pressure level of the aquifer. Artesian flow describes the natural flow to the surface of water from confined aquifers.	DWR	GLO21
21	yr	the time taken by the earth to make one revolution around the sun	DICT1	GLO22

GrainSize

OBJECTID	Map_Unit	Grain_Size_Distribution	Bedding	Sorting	Roundness	Color__per_Munsell_Color__1991_	Sand_Composition	Gravel_Composition	Secondary_Carbonate
1	Qa1	Sand is fine (fU) to coarse (cL), with rare cU; medium (mU) to coarse (cU), with minor medium (mL) sand and rare very coarse sand; rare gravel content is granules to pebbles up to 10 mm	Coarse interbeds 6–10 cm thick	Highly variable, ranging from well to very poorly sorted	Sand is angular to subangular with some subrounded; gravel is angular to subangular	Light gray (10YR), pinkish white (5YR) (both dry)	Quartz 85–90%, feldspar and others 5–14%, opaques from <1 to 5%, trace mica	Granitic	Absent
2	Qa2	Most locations are sand with fines scarce or absent. Sand is: very fine (vfL) to fine (fU) with rare medium (mL) sand; fine (fL or fU) to medium (mL) sand or coarse (cL) sand with minor vfs; and rare cU to vcs. Rare gravel content of granules up to 3 mm. Some locations are sandy clayey silt or sandy silty clay, with 30–50% sand content consisting of very fine (vfL) sand to coarse (cU) sand, with rare very coarse (vcL) sand, or very fine sand and trace mica (very fine). A few locations are clay with rare grains of medium sand	Sand locations (Bijou Creek) have bedding at 1–3 cm with cross bedding, channel scouring, lenticular bedding, coarsening–upward sequences, and laminated clay interbeds. In one location (Kiowa Creek), interbeds of clay and sand range from ~6–30 cm thick. Within these larger beds, dark–gray clay interbeds are 6–7 cm thick, sometimes with lighter silty interbeds 2–3 cm thick. Clay layers locally are massive, or have laminations and/or fragments of very fine sand, 1–5 mm thick	Sand deposits and sand fraction of clay deposits both are well to poorly sorted	Sand deposits are angular to subangular, or subangular to subrounded. Sand fraction in clay is subangular to subrounded with some rounded, or rarely angular to subangular	Sand: light brownish gray, light gray (10YR); light olive brown, light yellowish brown (2.5 Y) (all dry). Sandy clayey silt/sandy silty clay: dark gray, dark grayish brown, light brownish gray, white (10YR) (all dry)	Sand deposits are quartz 85–95%, feldspar and others 4–10%, opaques from <1 to 5%, with occasional trace mica up to 3 mm. Sand fraction in clay contains trace mica	Not noted	In most locations, no secondary carbonate apparent. In one location (Kiowa Creek), sandy clayey silt/sandy silty clay with very fine sand has a few very small carbonate nodules having violent effervescence. Some locations where nodules are not present have strong efferevescence. Coarser sand beds (fL to cL) have no apparent secondary carbonate
3	Qes	Sand is: dominantly, fine (fU) to medium (mU), with minor very fine sand and rare coarse (cL) to very coarse (vcU) sand; and subordinately, fine (fU) to coarse (cL) sand with minor very fine and rare coarse (cU) to very coarse (vcU) sand. Rarely, sand is very fine (vfU) to fine (fU) with rare medium sand; medium (mL–mU) sand with minor very fine to fine (fU) sand and rare coarse (cL) to very coarse (vcU) sand; and medium (mL) to coarse (cL) sand with minor very fine sand and rare coarse (cU) to very coarse (vcL) sand. In all above, rare gravel content of granules up to 3 mm	Planar bedding at 1–20 cm; beds often distinguished by differences in grain size; platy breakage (along bedding planes) seen in more-consolidated deposits	Poor to moderate, with rare well-sorted deposits	Dominantly subrounded to rounded; locally subangular to subrounded; rare well-rounded grains. Locally, the larger grains in a population are more rounded	Dominantly yellowish brown (10YR); less commonly olive brown, dark olive brown (2.5Y) (all dry)	Quartz 80–95%, feldspar and others 4–17%, opaques from <1 to 5%, with local trace mica up to 2 mm	Not noted	Absent, except a a single location having very rare scattered carbonate filaments and nodules
4	Qp	Most locations are silty clayey sand/clayey silty sand with 10–40% fines content; some locations are sandy clayey silt/sandy silty clay with 10–40% sand content consisting of fine (fU) to very coarse (vcU) sand, and granules up to 3 mm. Silty clayey sand/clayey silty sand is dominantly very fine (vfU) to fine (fU) and medium (mU) sand with rare coarse (cL) to very coarse (vcU) sand. At a few locations, this material is fine (fU) sand to medium (mU) or coarse (cL) sand, with minor very fine sand and rare coarse (cU) sand, and granules up to 3 mm; and medium (mL) to coarse (cL) sand with minor very fine to fine sand, and rare coarse (cU) to very coarse (vcL) sand. A thick (~3 m) fluvial-eolian clay deposit, with ~15% sand, occurs in the Kiowa Creek valley, adjacent to the south of Wiggins	Typically massive, but some locations have platy breakage and laminations; striations on polished planar faces are rarely present. Rarely, sand fraction concentrates in small masses up to 10 mm in diameter. Fluvial-eolian clay deposit in the Kiowa Creek valley is massive	Sand fraction in clay ranges from very poorly sorted to well sorted. Silty clayey sand/clayey silty sand is usually poorly to moderately sorted, rarely well sorted	Sand fraction in clay is subangular to subrounded, very rarely with some rounded grains. Silty clayey sand/clayey silty sand is subangular to subrounded, rarely with some rounded grains	Color ranges from dark yellowish brown (10YR) to dark olive brown (2.5Y) (both moist). Fluvial-eolian clay is grayish brown and dark gray (2.5Y), and dark gray (10YR)	Silty clayey sand/clayey silty sand is quartz 85–90%, feldspar and others 4–14%, opaques from <1 to 5%, trace mica at many locations. Sand fraction in clay contains trace mica	Granitic	At some locations no secondary carbonate is apparent. At others, carbonate filaments 1–2 mm thick and up to 10 mm long, and(or) nodules up to 15 mm are present. Filaments range from 3–10% of mass and nodules may occupy up to 20–25% of mass. Filaments and nodules typically efferevesce violently, whereas the surrounding mass effervesces weakly to moderately. Carbonate occasionally fills fractures in samples. Fluvial-eolian clay commonly has no visible carbonate, has rare carbonate filaments 1–15 mm long, and locally has weak effervescence

MiscellaneousMapInformation

OBJECTID	MapProperty	MapPropertyValue	MiscellaneousMapInformation_ID
1	REFERENCES1	Berry, M.E., Slate, J.L., Hanson, P.R., and Brandt, T.R., 2015a, Geologic map of the Orchard 7.5’ quadrangle, Morgan County, Colorado: U.S. Geological Survey Special Investigations Map 3331, scale 1:24,000. [Also available at https://pubs.er.usgs.gov/publication/sim3331.] Berry, M.E., Slate, J.L., Paces, J.B., Hanson, P.R., and Brandt, T.R., 2015b, Geologic map of the Masters 7.5’ quadrangle, Weld and Morgan Counties, Colorado: U.S. Geological Survey Special Investigations Map 3344, scale 1:24,000. [Also available at https://pubs.er.usgs.gov/publication/sim3344.] Berry, M.E., Slate, J.L., and Taylor, E.M., 2019, Pleistocene and Holocene landscape development of the South Platte River corridor, northeastern Colorado: U.S. Geological Survey Scientific Investigations Report 2019–5020, 22 p. [Also available at https://pubs.er.usgs.gov/search?q=Pleistocene+and+Holocene+landscape+development+of+the+South+Platte+River+corridor%2C+northeastern+Colorado.] Birkeland, P.W., 1999, Soils and geomorphology: New York, Oxford University Press, 430 p. Bjorklund, L.J., and Brown, R.F., 1957, Geology and ground-water resources of the lower South Platte River Valley between Hardin Colorado, and Paxton Nebraska: U.S. Geological Survey Water-Supply Paper 1378, 431 p. [Also available at https://doi.org/10.3133/wsp1378.] Braddock, W.A., Nutalaya, P., and Colton, R.B., 1988, Geologic map of the Carter Lake Reservoir quadrangle, Boulder and Larimer Counties, Colorado: U.S. Geological Survey Geologic Quadrangle Map GQ-1628, scale 1:24,000. [Also available at https://pubs.er.usgs.gov/publication/gq1628.] Colorado Division of Reclamation, Mining, and Safety, 2020, Reports and Data, GIS Data, AUGER (map of mine permits), accessed 2022 at https://drms.colorado.gov/data-search. Colorado Division of Water Resources (DWR), 2022, Drillers' logs incorporated with water-well permits in online interactive map, accessed 2022, at https://maps.dnrgis.state.co.us/dwr/Index.html?viewer=dwrwellpermit. Colorado Oil and Gas Conservation Commission, 2023, Geologic unit contacts incorporated with oil and gas well data, interactive map, accessed 2023, at https://cogccmap.state.co.us/cogcc_gis_online/. Colorado Oil and Gas Conservation Commission, 2022, Oil and gas production data, accessed 2022, at https://cogcc.state.co.us/data.html#/cogis.] Dechesne, Marieke, Raynolds, R.G., Barkmann, P.E., and Johnson, K.R., 2011, Notes on the Denver Basin geologic maps — bedrock geology, structure, and isopach maps of the Upper Cretaceous to Paleogene strata between Greeley and Colorado Springs, Colorado: Colorado Geological Survey Open-File Report 11-01, 35 p. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-stratigraphy-notes-denver-basin-colorado/.] Galbraith, R.F., and Green, P.F., 1990, Estimating the component ages in a finite mixture, International Journal of Radiation Applications and Instrumentation, Part D, Nuclear Tracks and Radiation Measurements: v. 17, issue 3, p. 197-206. Galbraith, R.F., and Roberts, R.G., 2012, Statistical aspects of equivalent dose and error calculation and display in OSL dating: An overview and some recommendations: Quaternary Geochronology, v. 11, p. 1–27. Hemborg, H.T., 1996, Basement structure map of Colorado with oil and gas fields: Colorado Geological Survey Map Series 30, scale 1:1,000,000. [Also available at https://coloradogeologicalsurvey.org/publications/basement-structure-map-major-oil-gas-colorado/.] International Union of Geological Sciences, International Commission on Stratigraphy, 2023, International Chronostratigraphic Chart, v 2023/09. Keller, S.M., Lindsey, K.O., and Morgan, M.L., 2017, Geologic map of the Berthoud quadrangle, Larimer, Weld, and Boulder Counties, Colorado: Colorado Geological Survey Open-File Report 17-03, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-berthoud-quadrangle-boulder-larimer-weld-colorado/.] Keller, S.M., Lindsey, K.O., and Morgan, M.L., 2019, Geologic map of the Gowanda quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 19-02, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-gowanda-quadrangle-weld-colorado/.] Keller, S.M., and Marr, A.E., 2023a, Geologic map of the Valley View School quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 21-02, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-valley-view-school-quadrangle-weld-colorado/.] Keller, S.M., and Marr, A.E., 2023b, Geologic map of the Windsor quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 22-08, scale 1:24,000 (in publication). Keller, S.M., and Morgan, M.L., 2018, Geologic map of the Frederick quadrangle, Weld and Boulder Counties, Colorado: Colorado Geological Survey Open-File Report 18-01, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-frederick-quadrangle-weld-broomfield-colorado/.] Keller, S.M., and Morgan, M.L., 2020, Geologic map of the Greeley quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 20-05, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-greeley-quadrangle-weld-colorado/.] Kellogg, K.S., Shroba, R.R., Bryant, Bruce, and Premo, W.R., 2008, Geologic map of the Denver West 30′ × 60′ quadrangle, north-central Colorado: U.S. Geological Survey Scientific Investigations Map SIM–3000, scale 1:100,000, 48 p. pamphlet. [Also available at https://doi.org/10.3133/sim3000.] Langford, R.P., 1989, Fluvial-eolian interactions: Part 1, modern systems: Sedimentology, v. 36, p. 1023-1035.	MMI1
2	REFERENCES3	Scott, G.R., 1960, Subdivision of the Quaternary alluvium east of the Front Range near Denver, Colorado: Geological Society of America Bulletin, v. 71, no. 10, p. 1541−1543. [Also available at https://doi.org/10.1130/0016-7606(1960)10[1541:SOTQAE]2.0.CO;2.] Scott, G.R., 1978, Map showing geology, structure, and oil and gas fields in the Sterling 1o x 2o quadrangle, Colorado, Nebraska, and Kansas: U. S. Geological survey Miscellaneous Investigations Series Map I-1092 (two sheets), scale 1:250,000. [Also available at https://pubs.usgs.gov/publication/i1092.] Scott, G.R., and Cobban, W.A., 1965, Geologic and biostratigraphic map of the Pierre Shale between Jarre Creek and Loveland, Colorado: U.S. Geological Survey Miscellaneous Geological Investigations Map I-439, scale 1:48,000. [Also available at https://pubs.usgs.gov/imap/0439/report.pdf https://pubs.usgs.gov/imap/0439/plate-1.pdf] Slattery, J.S., Cobban, W.A. McKinney, K.C., Harries, P.J., and Sandness, A.L., 2013, Early Cretaceous to Paleocene paleogeography of the Western Interior Seaway: The interaction of eustasy and tectonism: Wyoming Geological Association 68th Annual Field Conference Guidebook, v. 68, p. 22-59. [Also available at https://www.academia.edu/14643564/Early_Cretaceous_to_Paleocene_Paleogeography_of_the_Western_Interior_Seaway_The_Interaction_of_Eustasy_and_Tectonism.] Spencer, F.D., 1986, Coal geology and coal, oil, and gas resources of the Erie and Frederick quadrangles, Boulder and Weld Counties, Colorado: U.S. Geological Survey Bulletin 1619, 58 p. [Also available at https://pubs.usgs.gov/bul/1619/report.pdf.] Topper, Ralf, Spray, K.L., Bellis, W.H., Hamilton, J.L., and Barkmann, P.E., 2003, Ground water atlas of Colorado: Colorado Geological Survey Special Publication 53, 210 p. [Also available at https://coloradogeologicalsurvey.org/water/colorado-groundwater-atlas/.] Town of Wiggins, Planning & Zoning Department, 2022, Geotechnical reports from several building projects within the Town of Wiggins (provided as unpublished pdf’s to Colorado Geological Survey). U.S. Department of Agriculture, Natural Resources Conservation Service, 2018, Assessing carbonates in the field with a dilute hydrochloric acid solution: Soil Survey Technical Note 5, 7 p. U.S. Federal Emergency Management Agency (FEMA), FEMA Flood Map Service Center, 2023, Flood maps 08087C0400E, 08087C0552D, and 08087C0555D (all in Wiggins 7.5’ quadrangle), accessed 2023, at https://msc.fema.gov/portal/search?AddressQuery=Morgan%20County%2C%20Colorado#searchresultsanchor. U.S. Geological Survey, 2022, Earthquake Hazards Program - Online Earthquake Catalog, accessed 2022, at https://earthquake.usgs.gov/earthquakes/search/. US GeoSupply, Incorporated, 2020, Grain size card comparator: Grand Junction, Colorado, accessed 2022 at https://www.usgeosupply.com/collections/reference-charts. Visual Color Systems, (no publication date), The Globe Soil Color Book, 2nd ed.: Visual Color Systems, Kingston, NY, 41 p. White, J.L., and Greenman, Celia, 2008, Collapsible soils in Colorado: Colorado Geological Survey Engineering Geology 14, 108 p. [Also available at https://coloradogeologicalsurvey.org/2018/28848-collapsible-soils/.] Wintle, A.G., and Murray, Andrew, 2006, A review of optically stimulated luminescence characteristic and their relevance in single-aliquot regeneration dating protocols: Radiation Measurements, v. 41. p. 369-391 [Also available at https://www.researchgate.net/publication/222128786_A_review_of_optically_stimulated_luminescence_characteristic_and_their_relevance_in_single-aliquot_regeneration_dating_protocols.]	MMI2
3	ACKNOWLEDGMENTS	The authors sincerely thank the following for their assistance with the Wiggins quadrangle mapping project. Ralph Shroba, Scientist Emeritus with the U.S. Geological Survey and geologist with the Colorado Geological Survey (CGS), was the peer reviewer and his valuable suggestions improved this map. Scot Fitzgerald of the CGS assembled the lidar imagery for the quadrangle and surrounding area. Alexander Marr of the CGS compiled the water well drillers’ logs in support of the Quaternary cross sections. Steven Forman of Baylor University, Waco, Texas performed the optically stimulated luminescence (OSL) analyses, and Beta Analytic, Inc. in Miami, Florida performed the radiocarbon analyses. Hope Becker, Planning & Zoning Administrator for the Town of Wiggins, provided copies of geotechnical reports containing borehole logs. Caitlin Bernier of Pangaea Geospatial, Gunnison, Colorado produced the final map plates and GIS files. Jonathan White, CGS STATEMAP Program Manager and Matthew Morgan, State Geologist and CGS Director, reviewed the final publication. We are grateful to the many landowners in the Wiggins quadrangle who permitted us to visit and work on their properties, and to the contractors who allowed us to examine and sample their trenches and foundation excavations. We also thank the Colorado State Land Board for facilitating access to certain properties. All this assistance was invaluable to our geologic research and enabled the completion of this geologic map.	MMI3
4	GEOLOGIC HISTORY1	The Wiggins quadrangle lies in the northeast part of the Colorado Piedmont, a widespread erosional feature below the foothills of the Front Range Topographic relief in the piedmont is relatively low. The quadrangle has only 82 m of elevation difference between its lowest elevation (1,372 m, where Bijou Creek crosses the quadrangle’s north boundary) and highest elevation (1,454 m, in the quadrangle’s southwest corner). Approximately three-quarters of the quadrangle consists of wide, generally north-to-south-trending valleys containing alluvial sand, silt, and clay at the ground surface and some alluvial gravel at depth. Approximately one-quarter consists of intervening uplands covered with eolian sand, with pond and sheetwash deposits in some of the flat depressions in the dune fields (see geologic map, Plate 1). Eolian sand uplands are bedrock-cored on the east and southwest parts of the quadrangle but not in the center. A thin band of weathered bedrock (Pierre Shale Upper Transition Member) is exposed on the east valley wall of Bijou Creek in the northeast portion of the quadrangle. The relatively few natural exposures of the alluvial and eolian sediments occur in valley walls and cut banks of streams. Bedrock topography beneath alluvial valleys is generally aligned with valley surface topography, except in the center of the quadrangle, where the eolian sand upland has no bedrock core and is underlain by Middle Holocene to Late Pleistocene alluvium. The Wiggins quadrangle is near the northeast extent of the Denver Basin, as indicated by a regional map of the basin and by a structure contour map on the top of the Fox Hills Sandstone (Dechesne and others, 2011). This formation is the youngest bedrock unit present in the quadrangle but has no surface exposure. Also from the structure contour map, the Fox Hills Sandstone in the vicinity of the Wiggins quadrangle dips to the west at ~0.2 degrees. Cross section A-A’ indicates that the bedrock units beneath the Wiggins quadrangle are nearly flat-lying. All the bedrock units shown in cross section A-A’ are Cretaceous members, formations, or groups formed from sediments deposited in the Western Interior Seaway, which at its maximum extent reached from the Arctic Ocean to the Gulf of Mexico and divided the North American continent. From Middle Jurassic into Late Cretaceous time the seaway occupied the Western Interior Foreland Basin east of the Cordilleran Orogenic Belt. The basin and orogenic belt were formed as North America drifted westward away from Europe and as the Pacific (Panthalassan) oceanic crust was subducted beneath the North American Plate (Slattery and others, 2013). The Laramide orogeny during Late Cretaceous and Paleogene time, along with a drop in eustatic sea level, caused the Western Interior Seaway to retreat from the interior of North America. The Late Cretaceous Fox Hills Sandstone is the youngest of the seaway’s marine deposits and is present (beneath Quaternary deposits) along the west boundary of the Wiggins quadrangle. This formation represents near-shore and beach environments on the western margin of the retreating seaway. The Upper Transition Member of the Pierre Shale underlies the Fox Hills Sandstone and represents the near-shore environment of the seaway. Because the Cretaceous strata dip gently westward, it is the Pierre Shale that underlies the Quaternary sediments in almost the entire quadrangle. The Dakota Group is the oldest geologic unit encountered by oil and gas drilling in the Wiggins quadrangle (cross section A-A’, Plate 2). The Cretaceous marine deposits in cross section A-A’ overlie a subsided package of Mesozoic and Paleozoic formations, and these in turn overlie Precambrian cratonic crystalline basement. For a description of geologic units older than the Dakota Group, and not appearing in the cross section, see Braddock and others (1988). The present-day landscape of the Colorado Piedmont between the Rocky Mountain Front Range and the High Plains Escarpment results chiefly from the downcutting and geomorphic evolution of the South Platte River and Arkansas River drainage basins mainly during late Neogene and Quaternary time, and was accelerated during Pleistocene glacial epochs. These processes began with removal of Paleogene and Neogene rocks and sediments that once covered Upper Cretaceous strata in these basins (Madole, 1991). The predominant Quaternary deposits in the piedmont, including those in the Wiggins quadrangle and surrounding area, are fluvial sediments of the South Platte River and its major tributaries, and eolian sediments (dune sand and loess) deflated from alluvium in the stream valleys and from upwind bedrock exposures (Madole, 1991; 2016). (Note that loess is not separately mapped in the Wiggins quadrangle, but that unit Qp could partly originate from loess deposition.)There are three active drainages and two inactive paleovalleys in the quadrangle. The three active drainages are Bijou Creek, Antelope Creek, Kiowa Creek; each of these is situated in a paleovalley. The inactive paleovalleys are informally named the County Road 3 paleovalley and the Empire Reservoir paleovalley (see geologic map, Plate 1). The two larger active drainages, Kiowa Creek and Bijou Creek, both originate north of the Palmer Divide, a high upland divide separating the drainage basins of the South Platte River to the north and Arkansas River to the south. The elevation of the Palmer Divide ranges between 1,829 and 2,404 m. The headwaters of both creeks are in northernmost El Paso County, ~140 km south-southwest of the town of Wiggins. Kiowa Creek flows north out of the Wiggins quadrangle to join the South Platte River at ~10 km north of the town of Wiggins. Bijou Creek flows north out of the Wiggins quadrangle for ~3 km, then turns east to join the South Platte River at ~17 km east of Wiggins. Antelope Creek flows north-northeast from the Hoyt quadrangle into the Wiggins quadrangle and joins Bijou Creek at ~6 km north of the Wiggins quadrangle south boundary. The Antelope Creek valley floor grades into the west terrace of the Bijou Creek valley. Lidar imagery suggests that the terraces bounding the Antelope Creek valley (at the south quadrangle boundary) are the maximum aggradation surface (Late Pleistocene to Middle Holocene) of a former, wider Bijou Creek valley. The Antelope Creek valley lacks unit Qa2 but contains a deposit of unit Qa1 too narrow to be mapped.	MMI4
5	GEOLOGIC HISTORY2	The County Road 3 paleovalley is a prominent topographic feature on the west side of the Wiggins quadrangle and extends south into the Hoyt quadrangle. Morgan County Road 3 runs north to south through the valley and the valley width is ~1.5 km. Formerly, the valley probably was part of the west side of the Bijou Creek valley. The County Road 3 drainage presently contains an unnamed intermittent stream that flows north only to between County Roads L and M and does not join Kiowa Creek. Lidar imagery interpretation indicates the County Road 3 valley floor has a few large mid-channel bars similar to those of the unit Qa3 east terrace in the Bijou Creek valley. The Empire Reservoir paleovalley formerly was a north-trending tributary to the South Platte River and may have been on the west side of a much wider combined Kiowa Creek and Bijou Creek paleovalley. The Empire Reservoir paleovalley is ~1 km wide and originates in the northwest corner of the Wiggins quadrangle and northeast corner of the Omar quadrangle (adjacent to the west of the Wiggins quadrangle). From the area (in the Wiggins quadrangle) between the Burlington Northern rail line and U.S. Interstate Highway I-76, the paleovalley trends north along the east side of Empire Reservoir (in the Masters quadrangle, to the north) and joins the South Platte River valley at ~6 km north of the Wiggins quadrangle northwest corner. During the Late Pleistocene glacial epoch both Bijou Creek and Kiowa Creek likely were braided stream systems occupying the entire widths of their respective modern valleys. The east ends of cross sections B-B’, C-C’, and D-D’ show the Bijou Creek valley as bounded to the east by bedrock upland of the Pierre Shale Upper Transitional Member, covered by eolian sand. The north-south-trending upland in the southwest corner of the Wiggins quadrangle has no recorded water wells and thus is not included in cross section D-D’. It does, however, appear to be a sand-covered bedrock upland bounding the County Road 3 drainage on the west and continuing south into the Hoyt quadrangle. To the south, in the topographic map of the Hoyt quadrangle, the County Road 3 drainage is not distinguishable, and the Bijou Creek valley is confined by bedrock upland on the west and east. The low relief of the bedrock surface on the west side of cross section D-D’ indicates that the County Road 3 drainage was not a distinct feature during the Late Pleistocene, but during that time was the western side of a larger Bijou Creek valley. It is probable that the County Road 3 drainage was blocked off from the Bijou Creek valley by Holocene accumulation of the eolian sand, creating the low upland hills that presently separate the two drainages. The Bijou Creek and Kiowa Creek drainages presently have markedly separate channels flowing to the South Platte River, their junctions being respectively east and north of the Wiggins quadrangle, but lidar imagery interpretation and water well data suggest that their paleovalleys converged in the east-central part of the quadrangle. The convergence appears to be near where County Road 2 crosses modern Kiowa Creek. South and upstream from there the Kiowa Creek paleovalley is separated from the Bijou Creek paleovalley by the extensive sand-covered bedrock upland in the southwest corner of the quadrangle. North of the convergence, a low-relief bedrock surface, shown in cross sections B-B’ and C-C’, indicates a continuous bedrock valley floor underlying the modern courses of both creeks. Probably during Late Pleistocene through Middle Holocene time, the extensive eolian sand upland lying south of the town of Wiggins (cross section C-C’) was deposited in the area of paleovalley convergence and now separates the two modern valleys. This upland has no bedrock core, and its eolian sand overlies alluvium of unit Qa3. Upstream and north along the trend of the combined paleovalleys, the topographic map of the Orchard quadrangle (adjacent to the north of the Wiggins quadrangle) shows a broad, fan-like surface extending from the Wiggins quadrangle north boundary to the south bluff of the South Platte River valley. The geologic map of the Orchard quadrangle (Berry and others, 2015a) shows Broadway sidestream deposits (unit Qbs, equivalent to unit Qa3 in the Wiggins quadrangle) to be exposed all along the south bluff of the South Platte River valley. This deposit appears to be continuous with unit Qa3 sediments deposited in the combined paleovalleys of Kiowa Creek and Bijou Creek in the Wiggins quadrangle. The modern drainages of Bijou Creek, Kiowa Creek, and the Empire Reservoir paleovalley all are incised in the above fan-like surface. Kiowa Creek and the Empire Reservoir drainage head north along the trend of the combined paleovalleys, but the Bijou Creek incision has been diverted about 90 degrees to the east, possibly by avulsion during the Holocene. Bjorklund and Brown (1957) state that at present the South Platte River is flowing at grade, a condition in which erosion and deposition are approximately equal, but that its tributaries, including Bijou Creek, are still actively eroding because they are not yet adjusted to the river. The topographic base in the geologic map (Plate 1) indicates that the fill-terrace elevations of the Kiowa Creek valley floor and the western valley floor of Bijou Creek are comparable, with a difference in elevation of less than 2 m. In both valleys, in areas covered by the youngest alluvium of unit Qa3, lidar imagery interpretation indicates that there are a few large mid-channel bars oriented parallel to the direction of paleoflow during the time when the youngest sediments of the unit Qa3 fill terrace were deposited. The bars are about ~800 to 1,200 m long, ~70 to 90 m wide, and as high as 2 m. The Kiowa Creek and Bijou Creek valleys have been differentially incised in the Holocene. This is supported by the following observations made from the lidar imagery: 1) in the Kiowa Creek valley, unit Qa3 is only a little incised, whereas in the Bijou Creek valley the deposit is markedly incised; 2) in the Kiowa Creek valley there are no fill-cut terraces within unit Qa3, whereas there are many such terraces in the Bijou Creek valley; 3) in the Kiowa Creek valley, unit Qa2 terraces are few and narrow (~200-m wide), whereas in the Bijou Creek valley they are multiple and wide (up to 1,200 m); and 4) in the Kiowa Creek valley the incision occupied by unit Qa1 is narrow (15 m or less), whereas in the Bijou Creek valley the incision is much wider (up to 260 m).	MMI5
6	GEOLOGIC HISTORY3	Several terrace elevation profiles were plotted across the Bijou Creek and Kiowa Creek valleys, using elevation data from the Wiggins quadrangle lidar digital elevation model (DEM). Lidar DEM modeling clearly identifies the fill terraces of Bijou Creek and Kiowa Creeks. These highest terraces are assumed to be the maximum elevations of Late Pleistocene to Middle Holocene aggradation of unit Qa3, associated with Pinedale glaciation in the Rocky Mountains and extending into post-Pinedale time. The fill terrace of the Bijou Creek valley bounds three lower levels of fill-cut terraces, indicating periods of incision and lateral erosion during post-Pinedale time. The terraces occur on both sides of the valley, only one set is paired (i.e., same elevation on opposite valley sides), and exposed incision depths (heights of terrace risers) are 0.6–2.1 m on the west side of the valley, where areas of two or three stepped terraces occur. In the Kiowa Creek valley there are no fill-cut terraces in unit Qa3. In the Bijou Creek valley the elevation difference between the fill terraces of units Qa3 and Qa2 is 5.2–6.7 m, and the difference between the fill terraces of units Qa2 and the top of Qa1 deposits is 1.8–2.7 m. In the Kiowa Creek valley (where only one deposit of unit Qa2 is mapped), the elevation difference between fill terraces of units Qa3 and Qa2 is 3.0 m, and the difference between the fill terrace of units Qa2 and the top of Qa1 deposits is 1.5 m. Therefore, it appears that post-Pinedale incision in the Kiowa Creek valley was much less developed than in the Bijou Creek valley. The optically stimulated luminescence (OSL) age of the near-surface part of unit Qa3 alluvium (top of Kiowa Creek valley fill) is ~9.8 ky. In a unit Qa3 fill-cut terrace within the Bijou Creek valley the OSL age is ~6.1 ky (sample WS025OSL). (For sample locations see the geologic map in Plate 1; for OSL ages with error ranges see Table 2.) The Orchard and Weldona quadrangles are adjacent to the Wiggins quadrangle on the north and northeast, respectively. Berry and others’ (2015a, 2015b) unit Qbs in these two quadrangles is continuous with unit Qa3 in the Wiggins quadrangle. The above two CGS ages for unit Qa3 are Early and Middle Holocene, respectively. Ages for unit Qbs in the Orchard and Weldona quadrangles are Late Pleistocene to Early Holocene: ~15.2 ky (OSL), ~14.6 ky (OSL), ~14.5 ky (radiocarbon), ~12.4 ky (OSL), ~12.0 ky (OSL), and ~9.4 ky (OSL) (Berry and others, 2015a, 2015b). Kellogg and others (2008) give an age range of 12–30 ky for Broadway Alluvium (unit Qa3 equivalent) in the northern Colorado Piedmont and correlate it with Pinedale glaciation in the Rocky Mountains. Unit Qa3 (Pinedale equivalent) ages are approximately 11–18 ky (Madole, 2016; Keller and others, 2017; Palkovic and others, 2018; Keller and Marr, 2023b; Lindsey and Palkovic, 2020). In the northern Colorado Piedmont there is, however, a group of CGS ages for unit Qa3(?) that do not correlate either with Pinedale glaciation or with CGS unit Qa4 (Louviers Alluvium; Scott, 1960), which has an age of 120–170 ky and is associated with the older Bull Lake glaciation (Kellogg and others, 2008). These intermediate ages are approximately 40–87 ky (Keller and others, 2019; Keller and Morgan, 2020; Lindsey and Palkovic, 2020; Palkovic, 2020). An explanation for this group of ages intermediate between those of the Pinedale and Bull Lake glaciations has not yet been advanced and is a possible subject for further investigation. The two CGS Wiggins quadrangle ages for unit Qa3 (~9.8 ky and ~6.1 ky) are Early to Middle Holocene and are notably younger than the above Late Pleistocene ages for unit Qa3 and Berry and others’ (2015a, 2015b) unit Qbs. These two ages probably represent the maximum aggradation of unit Qa3 in the Kiowa Creek and Bijou Creek valleys, during a period lasting for some time after Pinedale glaciation. Up through Middle Holocene time the aggradation rates of unit Qa3 in Kiowa Creek and Bijou Creek apparently were similar because the present valley floors are at approximately the same elevation. During the Early Holocene these two north-flowing drainages possibly received sediment from erosion of eolian sand fields. During the Middle Holocene, after aggradation had ceased, incision apparently affected the Kiowa Creek valley much less than the Bijou Creek valley. Stream flow in both creeks likely was considerably reduced during post-Pinedale incision, but stream flow in Kiowa Creek, relative to that of Bijou Creek, apparently decreased from what it had been during maximum aggradation. If the relative flows of both creeks had remained the same or similar after aggradation ceased (even while the flows in both streams were reduced), incision and terrace development of the Kiowa Creek valley would be similar to the Bijou Creek valley. A hypothesis for inferred Middle Holocene diminution of Kiowa Creek flow relative to Bijou Creek flow is a possible subject for further investigation. About 1 km south of the town of Wiggins there is a south-trending series of five unconnected deposits of unit Qp enclosed by eolian sand unit Qes, between the Kiowa Creek and Bijou Creek valleys (see geologic map, Plate 1). The top elevations of these deposits are several meters lower than the Kiowa Creek and Bijou Creek valley floors. It is presumed that unit Qp was deposited in interdune depressions in the dune field. Based on this presumption, cross sections C-C’ and D-D’ depict the base of unit Qes as also being lower in elevation than the present valley floors. Water well logs supporting the depiction of unit Qa3 in the three Quaternary cross sections indicate that alluvial sediments (including gravel layers) underlie the dune field. Therefore, it is probable that the dune field was initially deposited on a topographically lower, Late Pleistocene unit Qa3 valley-fill surface. Thus, during the initial deposition of eolian sand, the interdune depressions were higher than the contemporary valley floors. As the creek valleys aggraded to their maximum elevations during the Middle Holocene, their valley fills became high enough to allow their groundwater to infiltrate the lower deposits of unit Qes. During times of high water table, such as during flood events, heavy precipitation events, and (or) seasonal fluctuations, groundwater from the valley fill may have infiltrated into the low interdune areas and formed temporary ponds in which pond and sheetwash sediments (unit Qp) were deposited during the Middle Holocene. Note that unit Qp at sample location WS137BC14 (geologic map, Plate 1) has a radiocarbon age of ~6.1 ky, which is younger than the OSL age of ~12.8 ky for unit Qes at sample location WS111OSL (Table 2). Deflation of fines from Kiowa Creek valley alluvium and perhaps more distant sources, entrapment of fine eolian particles during times of open water, sheetwash from the surrounding sand dunes, and minor winnowing of fines from the dunes may have been sources for the sand and fines in the interdune unit Qp sediments.	MMI6
7	MINERAL RESOURCES1	Within the Wiggins quadrangle there are no active or inactive construction permits for aggregate production and there are no active or inactive mining permits for other commodities (Colorado Division of Reclamation, Mining and Safety, AUGER interactive map, 2023). An inactive sand pit is located ~1.6 km south of Wiggins. It was excavated in unit Qes (eolian deposits) and unit Qp (pond deposits) and occupies an elongate area of ~0.05 km2. No sand or aggregate extraction operations were observed in the quadrangle during the summer 2022 field work for this map. As recorded in the drillers’ logs (Colorado Division of Water Resources [DWR], 2022) used to assemble cross sections B-B’, C-C’, and D-D’, almost all the water wells in the valleys of Kiowa Creek and Bijou Creek encountered gravel layers in unit Qa3. Overall, the gravel layers are 2–34 m thick, many of the layers are 17–34 m thick, tops of layers are 3–44 m below ground surface, and in many places the layers cannot be correlated between adjacent wells. The last characteristic probably owes to the lateral variability of sediments in braided streams and the general nature of the descriptions in drillers’ logs. Because of the presence of gravel layers, unit Qa3 can be considered a possible but untested aggregate resource in the stream valleys in the Wiggins quadrangle. During the summer 2022 field work for this map there was no oil and gas activity, or past or present oil and gas infrastructure (e.g., drilling rigs, pumping wells, storage tanks, warning signs for gas pipelines, etc.), observed within the Wiggins quadrangle, although some infrastructure from past activity may exist. A map of Colorado oil and gas fields in Hemborg (1996) shows that there were no oil or gas fields in the Wiggins quadrangle as of 1996. The map shows two small oil fields and three small gas fields in adjacent quadrangles. The largest of these is the Swan oil field in the Masters quadrangle (adjoining the Wiggins quadrangle to the northwest), covering ~33 km2. The closest is the Vallery gas field, covering ~9 km2 in the north-central part of the Vallery quadrangle (adjoining the Wiggins quadrangle to the east). According to data from the Colorado Energy and Carbon Management Commission (ECMC) web site (accessed in 2022), there were from 1953 to 1998 a total of 43 oil and gas wells drilled in the Wiggins quadrangle: 17 during the 1950s, four during the 1960s, 14 during the 1970s, six during the 1980s, and two during the 1990s. In the ECMC records the recorded formation tops are almost entirely for the Niobrara Formation, Colorado Group, and Dakota Group (see cross section A-A’), and these rock units apparently were the exploration targets. In records for all but five of the 43 oil and gas wells, the ECMC site displays a note that no production records were found. For the five wells for which either production or testing is noted, three were tested in the D sand or J sand of the Dakota Group, but no testing results appear in the records. One well had oil production from the D sand (year unspecified), and another well had production from 1999 to 2008 (but not specified whether oil or gas production); the production quantity is not given for either of these wells. In summary, the Wiggins quadrangle appears to have little oil and gas potential under current economic and earlier technological conditions. This is suggested by the above data and by the lack of exploration drilling records later than 1998. In contrast, the Wattenberg oil and gas field, the center of which is ~60 km west of Wiggins, currently has high rates of oil and gas production from the same formations that were unsuccessfully explored in the Wiggins quadrangle. However, previous drilling in the Wiggins quadrangle occurred prior to current horizontal drilling and fracking well-completion technologies.	MMI7
8	MINERAL RESOURCES2	During the mid-1970s there was a period of uranium exploration activity targeting the Fox Hills Sandstone in northeast Colorado. The objective was to discover roll-front uranium deposits amenable to in-situ uranium extraction. During the 2000s the Colorado Geological Survey (CGS) collaborated with the Denver Museum of Nature and Science in a study of the bedrock geology and structure of the Denver Basin (Dechesne and others, 2011), including the Fox Hills Sandstone. The investigators were provided with uranium exploration drilling records and borehole geophysical logs for a uranium target area in the Omar quadrangle and other adjacent quadrangles west of the Wiggins quadrangle. The target area is ~40 km long and ~15 km wide, trends northeast to southeast along the furthest eastward extent of the Fox Hills Sandstone, lies along the eastern margin of the Denver Basin, and contains 71 exploration boreholes. The recorded borehole depths increase from northeast to southwest as the top of the Fox Hills Sandstone deepens toward the Denver Basin axis; borehole depths range from 50 to 165 m. The Fox Hills Sandstone impinges only a little on the Wiggins quadrangle, in the southwest corner. Only one of the boreholes is within the Wiggins quadrangle. It is east of the Fox Hills Sandstone subcrop (the formation is buried by unit Qes) and apparently (per its depth of 76 m) was drilled in unit Qa3 and Pierre Shale. Based upon the above data, the Wiggins quadrangle has little potential for uranium resources. There were 229 permitted water wells in the Wiggins quadrangle as of 2022 (Colorado Division of Water Resources interactive well permit map, 2022). Of this total, 204 wells are situated in the unit Qa3 alluvial aquifers of the principal drainages: Bijou Creek, Kiowa Creek, Antelope Creek, County Road 3 paleovalley, and Empire Reservoir paleovalley (see geologic map on Plate 1 for drainage labels). These wells mainly are for agricultural use. Eight water wells are in the valley aquifer of unit Qa2 in the Bijou Creek valley and 17 wells are in areas covered by unit Qes. The thickness of the unit Qa3 and unit Qa2 alluviums, and some representative depths of the water wells, are shown in cross sections B-B’, C-C’, and D-D’. Unit Qa3 alluvium consists of interbedded layers of sand, gravel, and clayey silt or silty clay and is underlain by the relatively impermeable Pierre Shale. In the northern Colorado Piedmont this alluvium is present in the valleys of the South Platte River and its major tributaries as well as in minor paleovalleys that formerly were tributary to these streams. Alluvial aquifers in the South Platte River Basin are presented and discussed in Topper and others (2003). Permitted pumping rates for water wells are part of the data accessible through the DWR interactive map, and rates for 80 Wiggins quadrangle wells were assembled: 40 in the Kiowa Creek valley and 40 in the Bijou Creek valley. In the Kiowa Creek valley there is a fairly even distribution of 37 permitted pumping rates between values of 700 and 1,800 gallons per minute (gpm), and four that range between 50 and 500 gpm. The average for the 37 wells is ~1,000 gpm. In the Bijou Creek valley there is a fairly even distribution for 40 pumping rates, with values between 700 and 1,950 gpm; the average rate is ~1,250 gpm. Three separate and contiguous flood maps, two published in 2018 and one in 2021, lie entirely within the boundaries of the Wiggins quadrangle and delineate flood hazards in the quadrangle (U.S. Federal Emergency Management Agency [FEMA], FEMA Flood Map Service Center, 2023). In the Bijou Creek valley, all the area mapped as units Qa1 and Qa2 (geologic map, Plate 1) is designated as a special flood hazard area: that is, an area subject to inundation by the 1% annual chance flood (formerly called the 100-year flood). The hazard area does not extend outward onto the unit Qa3 terraces on either side of the valley, the elevations of which are above those of units Qa1 and Qa2. The Antelope Creek valley is tributary to the Bijou Creek valley, and the lowest portion of the Antelope Creek valley also is a special flood hazard area; the maximum width of this hazard area is ~0.5 km. Nearly all the Kiowa Creek valley is mapped as unit Qa3 except for small portions mapped as units Qp and Qa2, and nearly all the valley is designated as a special flood hazard area. Two separate areas in the valley, in the centers of sec. 16 and sec. 21, T. 3 N., R. 60 W., respectively, are designated as areas of 0.2% annual chance flood, as is nearly all the town of Wiggins plus an area of ~0.5 km2 extending southwest of the town and along the east side of the Kiowa Creek valley. There is an unnamed intermittent stream on the west side of the County Road 3 paleovalley, in the southwest corner of the quadrangle, and along this stream a band ~ 0.3 km wide is designated as a special flood hazard area. The Empire Reservoir paleovalley, in the northwest corner of the Wiggins quadrangle, does not have a flood hazard designation. Sediments that have a large enough fines fraction (silt and clay) can be collapsible soils or swelling (expansive) soils. In collapsible soils, the fines fraction gives the soil a relatively high compressive strength and shear strength under dry conditions. When wet or saturated, and under load, the fine-grained particles in these deposits can be displaced into a denser configuration such that the void space between particles is reduced. Compaction and associated decrease in volume can cause settlement at and near the ground surface, potentially resulting in damage to any overlying structures and (or) infrastructure (White and Greenman, 2008). In swelling soils, clay minerals (particularly bentonite) attract and absorb water, causing the clay in the sediment to increase in volume when wetted and decrease in volume when dried (Noe and others, 2014). This property of swelling and shrinking poses a geologic hazard to building foundations, other structures, and infrastructure. Watering of lawns, shrubs, and trees, a practice associated with urbanization and land development, promotes an increase in water percolating downward and results in deeper subsurface wetting of the sediments. Geotechnical site reports for several recent building projects in the town of Wiggins were made available for this report (Town of Wiggins Planning & Zoning Department, 2022). The town lies in an area mapped as unit Qa3 (geologic map, Plate 1). Geotechnical borehole logs in the geotechnical site reports typically range in depth from 3–6 m with a few at 10–12 m. Substrate less than 3 m below ground surface, a depth which would include most residential building foundations, is recorded in the logs as clayey sand, silty clay, and silty sand (none of the geotechnical reports contain particle size analyses). In the site reports, the unit Qa3 substrate in the town is described as having a low volume change accompanying an induced variation in moisture content and load, and as having no swell potential to low swell potential. Fines content is variable in unit Qa3 and the deposit covers most of the Wiggins quadrangle. Therefore, a geologic hazard due to collapsible or swelling soils could exist elsewhere in the quadrangle than in the town of Wiggins.	MMI8
9	STATEMAP AGREEMENT	This mapping project was funded jointly by the Colorado Geological Survey and the U.S. Geological Survey through the National Cooperative Mapping Program under STATEMAP agreement G22AC00302.	MMI9
10	TITLE	GEOLOGIC MAP OF THE WIGGINS QUADRANGLE MORGAN COUNTY, COLORADO	MMI10
11	AUTHORS	Stephen M. Keller and Emily A. Perman	MMI11
12	YEAR	2024	MMI12
13	OF NUMBER	OF-23-06	MMI13
14	DOI	https://doi.org/10.58783/cgs.of2306.zluy3701	MMI14
15	REFERENCES2	Lindsey, D.A., Langer, W.H., and Knepper, D.H., Jr., 2005, Stratigraphy, lithology, and sedimentary features of Quaternary alluvial deposits of the South Platte River and some of its tributaries east of the Front Range, Colorado: U.S. Geological Survey Professional Paper 1705, 70 p. [Also available at https://pubs.usgs.gov/pp/2005/1705/pdf/PP1705.pdf.] Lindsey, K.O., and Palkovic, M.J., 2020, Geologic map of the Kersey quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 20-06, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-kersey-quadrangle-weld-colorado/.] Machette, M.N., 1985, Calcic soils of the southwestern United States: Geological Society of America Special Paper 2013, 21 p. [Also available at https://www.nrc.gov/docs/ML0037/ML003747879.pdf.] Madole, R.F., 1991, Colorado Piedmont, in Wayne, W.J., ed., Quaternary geology of the Northern Great Plains, Chap. 15 in Morrison, R.B., ed., Quaternary nonglacial geology — conterminous United States: Geological Society of America, The geology of North America, v. K-2, p. 456-462. [Also available at https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1572&context=geosciencefacpub.] Madole, R.F., 2016, Geologic map of the Longmont quadrangle, Boulder and Weld Counties, Colorado: Colorado Geological Survey Open-File Report 16-05, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-longmont-quadrangle-boulder-weld-colorado/.] Madole, R.F., VanSistine, D.P., and Michael, J.A., 2005, Distribution of late Quaternary wind-deposited sand in eastern Colorado: U.S. Geological Survey Scientific Investigations Map 2875 (scale 1:700,000). [Also available at https://pubs.er.usgs.gov/publication/sim2875.] Munsell Color, 1991, Munsell soil color charts, 1990 edition revised: Newburgh, NY, Macbeth Division of Kollmorgen Instruments Corp., 14 p. Murray, Andrew and Wintle, A. G., 2003, The single aliquot regenerative dose protocol: Potential for improvements in reliability: Radiation Measurements, v. 37, p. 377-381. Nichols, G., 2009, Sedimentology and stratigraphy (second edition): Wiley-Blackwell, Chichester (United Kingdom), 419 p. Noe, D.C., Jochim, C.L., and Rogers, W.P., 2014, A guide to swelling soil for Colorado homebuyers and homeowners, second edition: Colorado Geological Survey Special Publication (SP) 43, 68 p. Palkovic, M.J., 2020, Geologic map of the Bracewell quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 20-03, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-bracewell-quadrangle-weld-colorado/.] Palkovic, M.J., Lindsay, K.O., and Morgan, M.L., 2018, Geologic map of the Milliken quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 18-02, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-milliken-quadrangle-weld-colorado/.] Palkovic, M.J., Lindsay, K.O., and Morgan, M.L., 2019, Geologic map of the La Salle quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 19-03, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-la-salle-quadrangle-weld-colorado/.] Palkovic, M.J., and Morgan, M.L., 2021, Geologic map of the Hardin quadrangle, Weld County, Colorado: Colorado Geological Survey Open-File Report 21-02, scale 1:24,000. [Also available at https://coloradogeologicalsurvey.org/publications/geologic-map-hardin-quadrangle-weld-colorado/.] Peng, Liang, and Forman, S.L., 2019, LDAC: An Excel-based program for luminescence equivalent dose and burial age calculations: Ancient TL, v. 37, p. 21–40. Prescott, J.R., and Hutton, J.T., 1994, Cosmic ray contributions to dose rates for luminescence and ESR dating: large depths and long-term time variations: Radiation Measurements, v. 23, p. 497-500.	MMI15
16	GEOLOGIC HISTORY4	Two deposits of unit Qp are only partially enclosed by dunes. They are composed of silty clay or clayey silt and in excavation exposures are 3 m thick or greater. These unit Qp deposits are adjacent to and southwest of the town of Wiggins (radiocarbon age ~4.1 ky), and in the Kiowa Creek valley in the Omar quadrangle, ~3 km west of the Wiggins quadrangle west boundary (radiocarbon age ~3.4 ky) (see Table 2 for details on ages). These silty clay or clayey silt layers may represent sediments deposited in ephemeral ponds formed by temporary obstruction of Kiowa Creek channels by eolian sand. Alternatively, they may represent overbank flood deposits that accumulated where floodwater was impounded behind dunes and near stream channels. Both of these processes are presented in Langford (1989). The above unit Qp ages in the Kiowa Creek valley (~4.1 and 3.4 ky) are approximately contemporaneous with the radiocarbon age of Kiowa Creek unit Qa2 (~4.4 ky) at the west boundary of the Wiggins quadrangle, suggesting possible fluvial-eolian interaction in the Kiowa Creek valley during the Middle to Late Holocene. Lidar DEMs around the perimeter of the dune field separating the Kiowa Creek and Bijou Creek valleys suggest that aggrading unit Qa3 alluvium partially buried the southeast and northwest portions of the dune field, where some interdunes are only partially enclosed and could have been inundated by floods of Kiowa Creek and Bijou Creek. As presented above, eolian sand (unit Qes) from the dune-covered Pierre Shale upland on the east side of the Bijou Creek valley (geologic map, Plate 1) yielded an OSL age of ~12.8 ky (Late Pleistocene) (Table 2). Late Pleistocene eolian sand is extensive regionally (Madole and others, 2005, cited in Berry and others, 2015a), and Late Pleistocene eolian sand (~26 ky) occurs near Empire Reservoir in the southern part of the Masters quadrangle adjacent to the northwest of the Wiggins quadrangle (Berry and others, 2015b). Ages reported by Madole and others (2005) support the hypothesis that unit Qes eolian sand likely was first deposited on Bijou Creek alluvium during Late Pleistocene time. On the lidar image of the Bijou Creek valley, it appears that the uppermost deposits of unit Qa3 (younger, at ~6–10 ky) have enveloped the periphery of the unit Qes upland dune field (older, at ~13–26 ky) separating this valley from the County Road 3 paleovalley. A possible explanation is that the dune field was deposited in a combined, larger paleovalley during the early stage of unit Qa3 aggradation and when the valley floor elevation was lower. As the valley floor aggraded during the Late Pleistocene through Middle Holocene, unit Qa3 filled the lower areas within the outer part of the dune field. This interpretation, while supported by topography and age data, does not explain why the enveloped dunes do not appear to be truncated, how unit Qa3 came to be deposited in closed-off embayments in the dune field, or the lack of gravel layers in the upper portion of unit Qa3 near the dune field.	MMI16
17	MINERAL RESOURCES3	The Wiggins quadrangle appears to have only a low seismic risk. A search of the online U.S. Geological Survey Online Earthquake Catalog was performed using the following parameters: confined to within the quadrangle boundaries, covering the period from January 2003 to June 2023, listing seismic events of Richter magnitude 1 or greater, and listing events as deep as 3 km (a little lower than the deepest oil and gas wells in the quadrangle). The catalog reported no such seismic events.	MMI17

OSL

OBJECTID	Field_Sample_Number_and_Map_Location	Laboratory_Number	Map_Unit	Latitude	Longitude	Depth_Below_Ground_Surface__bgs___m_	Date_Collected	Material_Dated	Aliquotsa	Grain_Size__microns_	Equivalent_Dose__De__Gy_b	Overdispersion____c	U__ppm_d	Th__ppm_d	K2O____d	Rb__ppm_	H2O___	Cosmic_Dose_Rate__mGray_yr_e	Dose_Rate__mGray_yr_	SAR_OSL_age__yr_f
1	WS025OSL	5459	Qa3	40.23310075	-104.0408132	2.1	27-Jul-22	sand	37/46	355-500	15.66±0.5	38±5	2.34±0.01	10.45±0.01	3.81±0.01	107.5±0.01	10±3	0.213±0.021	3.55±0.12	6,125±255
2	WS059OSL	5460	Qa3	40.22871772	-104.0757908	0.8	10-Aug-22	sand	0.83	355-500	38.88±0.67	32±4	2.67±0.01	12.95±0.01	3.55±0.01	113.0±0.01	10±3	0.250±0.025	3.96±0.17	9,810±440
3	WS103OSLg	5461	Qa3	40.17881701	-104.0270254	1.4	9-Sep-22	sand	30/35	250-355	3.39±0.09	47±7	1.57±0.01	7.19±0.01	3.55±0.01	100.5±0.01	5±2	0.233±0.023	3.67±0.09	910±30
4	WS105OSL	5462	Qa2	40.18084372	-104.024062	1.1	9-Sep-22	sand	41/64	355-500	4.02±0.48	63±7	1.12±0.01	5.04±0.01	3.96±0.01	121.0±0.01	5±2	0.241±0.024	3.63±0.09	1,095±135
5	WS111OSL	5463	Qes	40.2157861	-104.0105205	2.2	21-Sep-22	sand	42/47	150-250	21.76±0.54	15±2	2.32±0.01	10.60±0.01	2.99±0.01	92.4±0.01	10±3	0.138±0.014	1.68±0.04	12,755±615

Qa3CharacteristicsTable

OBJECTID	Sediment_Type_and_Location	Grain_Size_Distribution	Bedding	Sorting	Roundness	Color__per_Munsell_Color__1991_	Sand_Composition	Gravel_Composition	Secondary_Carbonate
1	Bijou Creek valley	None	None	None	None	None	None	None	None
2	CLAYEY SILTY SAND: mostly on west terraces between County Roads L and Q	Clayey silty sand; sand mostly fine to coarse (fL to cU) with minor very fine and very coarse sand, minor granules and pebbles (locally), fines 15–40%	Not observed; most sample holes < 0.4 m deep	Poorly sorted (sand fraction)	Generally subangular to subrounded, locally subrounded to rounded (sand fraction)	Dark brown (2.5Y, moist), dark and very dark grayish brown (10YR, moist), brown (10YR, dry), dark brown (10YR, moist), very dark grayish brown (10YR, moist)	Quartz 80–90%, feldspar and others 9–19%, opaques <1%, trace mica	Granitic	Absent
3	VERY FINE TO MEDIUM SAND: on east terrace of valley, 2 km south of Fort Morgan water treatment plant, and terrace between Bijou Creek and Antelope Creek, near quadrangle south boundary	Very fine to medium sand with rare coarse to very coarse (cL to vcU) sand , rare granules, no fines; fine to coarse sand with rare granules, fines 10–20%	Not observed; most samples holes <0.4 m deep	Moderately to well sorted	Subangular to subrounded	Light olive brown (2.5Y), brown and dark grayish brown (10YR) (all dry)	Quartz 90%, feldspar and others 9%, opaques <1%	(Gravel absent)	Absent
4	MEDIUM TO COARSE SAND: on east terrace, 2 km south of Fort Morgan water treatment plant, and in northeast corner of quad; and west terrace between County Road O and County Road Q	Medium (mL to mU) to coarse or very coarse (cL to vcU) sand, with minor very fine to fine sand,fines 0–25%, rare granules and pebbles; locally, has interbeds of gravelly (granules and pebbles) sand, fine to medium sand with coarse to very coarse sand and no gravel, sandy clay, and medium sand to granules and pebbles	Where observed (rarely): 3 to 10 cm, 12 to 55 cm, 20 cm to 1 m	Poorly to moderately sorted	Generally subangular to subrounded, locally angular to subangular	Light yellowish brown, olive brown, light olive brown (2.5Y); brown, white, light gray (10YR) (all dry)	Quartz 85–90%, feldspar and others 9–14%, opaques <1%, trace mica	Granitic pebbles and clay fragments	Mostly absent; one location with carbonate zones and filaments; one location with carbonate rinds on pebbles (reworked from older alluvium?)
5	Antelope Creek valley	None	None	None	None	None	None	None	None
6	SANDY CLAYEY SILT; Antelope Creek valley	Sandy silty clay; fines 60–80%; sand fraction very fine to fine sand, very fine to medium (mU) sand with rare coarse sand and granules	Clayey silty sand interbeds (10 cm) (at single location); most bedding not observed because samples holes <0.4 m deep	Moderately to well sorted (sand fraction)	Subangular to subrounded (sand fraction)	Light olive brown (2.5Y, dry); dark grayish brown, olive brown (2.5Y, moist); brown, very dark grayish brown (10YR, moist)	Not noted	Not applicable	Absent
7	CLAYEY SILTY SAND; Antelope Creek valley	Clayey silty sand; fines 10–25%; sand fraction mostly fine to coarse (fL to cU) sand with minor very fine sand; also rare coarse to very coarse sand with rare granules and pebbles, and some very fine to medium (mU) sand with minor coarse to very coarse sand and rare granules and pebbles	Bedding at ~0.6 m (single location); bedding usually not observed because samples holes <0.4 m deep	Moderately to poorly sorted (sand fraction)	Subangular to subrounded (sand fraction)	Dark grayish brown (2.5Y, moist); light olive brown (2.5Y, dry); brown, grayish brown, dark grayish brown (10YR, dry)	Quartz 85–90%, feldspar and others 9–14%, opaques <1%, trace mica	Granitic	Absent
8	VERY FINE TO MEDIUM SAND; Antelope Creek valley	Very fine to medium sand with rare coarse to very coarse (cL to vcU) sand and rare granules and pebbles; usually no fines but fines 10% at one location	Not observed because samples holes <0.4 m deep	Moderately to poorly sorted	Subangular to subrounded	Brown, dark brown, yellowish brown (10YR, dry)	Quartz 85–90%, feldspar and others 9–14%, opaques 1%, trace mica	Granitic	Absent
9	Kiowa Creek valley	None	None	None	None	None	None	None	None
10	SANDY CLAYEY SILT: Kiowa Creek valley between Wiggins and west quadrangle boundary, and upstream in Omar quadrangle to west and downstream in Orchard quadrangle to north	Silty clay, sandy silty clay, sandy clayey silt; very fine to medium (mU) sand, with rare coarse sand to granules; fines 15–40%	Not observed; most sample holes <0.4 m deep	Poorly to very poorly sorted (sand fraction)	Subrounded to rounded (sand fraction)	Very dark grayish brown, grayish brown (2.5Y), brown (10YR) (all dry)	Quartz 85%, feldspar and others 14%, opaques <1%, trace mica	Granitic	Absent
11	CLAYEY SILTY SAND: at surface in Kiowa Creek valley from Omar quad downstream to north of Wiggins	Clayey silty sand; locally, sand fraction dominated by medium to coarse (mL to cL) sand with subordinate very fine to fine sand, and rare very coarse sand and granules, or dominated by very fine to medium sand with rare coarse to very coarse (cU to vcU) sand; fines fraction 10–30%	Not observed; most sample holes <0.4 m deep	Poorly sorted (sand fraction)	Subangular to subrounded (sand fraction)	Brown, dark brown, grayish brown, dark gray, very dark gray (10YR) (dry)	Quartz 85–90%, feldspar and others 9–14%, opaques <1%, trace mica	Granitic	No visible carbonate; weak efferevescence locally
12	FINE TO MEDIUM SAND: Kiowa Creek valley downstream from Wiggins	Fine to medium (fU to mU) sand with rare coarse sand to granules, fine to coarse (fU to cL) sand with minor very fine sand and minor fines, and rare very coarse sand and granitic granules and pebbles; no fines	Not observed; most sample holes <0.4 m deep	Poor to moderately sorted	Subangular to subrounded	Dark grayish brown, light olive brown) (2.5Y); light brownish gray, brown, pale brown (10YR) (all dry)	Quartz 85%, feldspar and others 14%, opaques <1%	Granitic	Absent
13	County Road 3 drainage	None	None	None	None	None	None	None	None
14	SANDY CLAYEY SILT; in valley from County Road L south to quadrangle south boundary	Sandy clayey silt; fines 50–80%; sand fraction fine to medium (fU to mU) sand with minor very fine sand, rare coarse sand to pebbles	Not observed because samples holes <0.4 m deep	Moderately sorted (sand fraction)	Subangular to subrounded (sand fraction)	Grayish brown, dark grayish brown (2.5Y, dry); light brownish gray (10YR, dry)	Not noted	Not noted	Absent
15	CLAYEY SILTY SAND; in valley from County Road M south to County Road L	Very fine to medium (mU) sand with rare coarse to very coarse sand, no gravel; fines 10–20%	Not observed because samples holes <0.4 m deep	Moderately sorted (sand fraction)	Subangular to subrounded (sand fraction)	Light olive brown (2.5Y, dry), dark grayish brown (10YR, dry)	Quartz 90%, feldspar and others 9%, opaques <1%, trace mica	Not applicable	Absent
16	Empire Reservoir drainage	None	None	None	None	None	None	None	None
17	CLAYEY SILTY SAND	Clayey silty sand; fines 40–70%; sand fraction fine to very coarse sand with rare very coarse sand to pebbles	Not observed because samples holes <0.4 m deep	Poorly to very poorly sorted (sand fraction)	Subangular to subrounded (sand fraction)	Brown, dark to very dark grayish brown (10YR, moist)	Quartz 85–90%, feldspar and others 9–14%, opaques <1%, trace mica	Not noted	Absent

c14

OBJECTID	Field_Sample_Number_and_Map_Location	Laboratory_Number	Map_Unit	Latitude	Longitude	Depth_Below_Ground_Surface__m_	Date_Collected	Material_Dated_and_Comments	delta13C__0_00_1	Conventional_Radiocarbon_Age__radiocarbon__B_P__2	Calibrated_Age_________________cal_B_P__3
1	WS060C142	Beta-653301	Qp	40.19595266	-104.1632724	1.0	8-Aug-22	Top of thick clay layer in pit at Robert Loose farm, in Kiowa Creek valley and 3.3 km west of west quadrangle boundary	-16.8	3,420±30	(85.8%) 3,724-3572 (8.1%) 3,822-3,795 (1.6%) 3,764-3,752
2	WS096C14	Beta-653302	Qp	40.2231291927724	-104.077719693329	0.8	1-Sep-22	Top of thick clay layer in tract home foundation pit	-20.8	4,090±30	(64.2%) 4,652-4,516 (18.6%) 4,808-4,705 (7%) 4,702-4,670 (5.6%) 4,476-4,446
3	WS099C14	Beta-653303	Qa2	40.1825943048937	-104.125658561289	2.3	2-Sep-22	Dark-colored (organic-rich?) clay in possible Qa2 terrace, Kiowa Creek valley	-19.9	4,420±30	(78.9%) 5,055-4,869 (14.8%) 5,270-5,186 (1.8%) 5,125-5,109
4	WS137BC14	Beta-653304	Qp	40.2110278619109	-104.07308680965	0.7	20-Oct-22	Silty or sandy clay, possibly lobe of Qi overlying Qes	-19.2	6,110±30	(72.4%) 7.032-6,888 (18.5%) 7,158-7,105 (4.5%) 7,074-7,040

This summary of database content is provided as a convenience to GIS analysts, reviewers, and others. It is not part of the GeMS compliance criteria.

DataSources, nonspatial table, 9 rows
DescriptionOfMapUnits, nonspatial table, 19 rows
GeoMaterialDict, nonspatial table, 101 rows
Glossary, nonspatial table, 24 rows
GrainSize, nonspatial table, 4 rows
MiscellaneousMapInformation, nonspatial table, 17 rows
OSL, nonspatial table, 5 rows
Qa3CharacteristicsTable, nonspatial table, 17 rows
c14, nonspatial table, 4 rows
GeologicMap, feature dataset
MapUnitPolys, simple polygon feature class, 101 rows
DataSourcePolys, simple polygon feature class, 2 rows
ContactsAndFaults, simple polyline feature class, 188 rows
CartographicLines, simple polyline feature class, 4 rows
GeochronPoints, simple point feature class, 9 rows
GenericPoints, simple point feature class, 71 rows
GeologicMap_topology, topology
MapUnitPolysAnno, annotation polygon feature class, 116 rows
GeochronPointsAnno, annotation polygon feature class, 8 rows
GenericPointsAnno, annotation polygon feature class, 71 rows
CorrelationOfMapUnits, feature dataset
CMUMapUnitPolys, simple polygon feature class, 11 rows
CMULines, simple polyline feature class, 18 rows
CMULinesAnno, annotation polygon feature class, 16 rows
CMUMapUnitPolysAnno, annotation polygon feature class, 11 rows
CrossSectionA, feature dataset
CSAMapUnitPolys, simple polygon feature class, 6 rows
CSA_DHTrace, simple polyline feature class, 10 rows
CSAMapUnitPolysAnno, annotation polygon feature class, 15 rows
CSA_PointsAnno, annotation polygon feature class, 29 rows
CSAContactsAndFaults, simple polyline feature class, 15 rows
CSAPoints, simple point feature class, 25 rows
CrossSectionB, feature dataset
CSBMapUnitPolys, simple polygon feature class, 11 rows
CSBDHTrace, simple polyline feature class, 21 rows
CSBPoints, simple point feature class, 33 rows
CSBPointsAnno, annotation polygon feature class, 36 rows
CSBMapUnitPolysAnno, annotation polygon feature class, 18 rows
CSBContactsAndFaults, simple polyline feature class, 30 rows
CrossSectionC, feature dataset
CSCMapUnitPolys, simple polygon feature class, 11 rows
CSCDHTrace, simple polyline feature class, 25 rows
CSCPoints, simple point feature class, 35 rows
CSCPointsAnno, annotation polygon feature class, 39 rows
CSCMapUnitPolysAnno, annotation polygon feature class, 16 rows
CSCContactsAndFaults, simple polyline feature class, 30 rows
CrossSectionD, feature dataset
CSDMapUnitPolys, simple polygon feature class, 7 rows
CSDDHTrace, simple polyline feature class, 15 rows
CSDPoints, simple point feature class, 23 rows
CSDPointsAnno, annotation polygon feature class, 26 rows
CSDMapUnitPolysAnno, annotation polygon feature class, 13 rows
CSDContactsAndFaults, simple polyline feature class, 18 rows