Jun 192017
 

Manitou Springs occupies a narrow valley where Fountain Creek emerges from the foothills northeast of Pikes Peak and west of Colorado Springs. The valley slopes are composed of interbedded resistant sandstone and conglomerates (i.e., gravelly sandstone), and weaker mudstones and shale. The outcropping sandstone is most prevalent on the steeper slopes on the north side of the valley.

During the wet spring of 1995, rockfall and landslides incidents increased throughout Colorado, some resulting in fatalities. In Manitou Springs, a fortunate set of circumstances occurred before the Memorial Day holiday weekend when local residents observed the movements of a large, dangerous block of rock before it actually could fall. The observation set into motion an emergency declaration by the town, resulting in a compulsory evacuation of homes located below the rocky slope, the closing of the road in the area, and an immediate rock stabilization project. During this emergency situation, the Colorado Geological Survey was asked to provide expert assistance to help stabilize the rock. The emergency evacuation decree remained in effect until the rock was stabilized and the area subsequently declared safe.

The ledge of jointed sandstone along with several large displaced blocks is seen at the center of the image. Photo credit Jon White.

The ledge of jointed sandstone along with several large displaced blocks is seen at the center of the image. Photo credit Jon White.

A prominent 12-foot-thick ledge of strongly-jointed sandstone forms the rim of this slope. Two essentially vertical and intersecting joint sets produce large orthogonal sandstone blocks that are being undermined by the more easily weathered mudstone beds below the ledge. The blocks begin to topple as the underlying rock that supports them erodes, creating dangerous overhangs. At the time of discovery, this particular block had moved 5.5 feet from the back face of the sandstone ledge and tilted precariously over the next sandstone ledge below. Had the 70-ton block fallen, it would have certainly crushed a home below.

A precarious rock above Manitou Springs started to move in 1995 after a period of wet weather. As an emergency measure, high-strength steel cables were wrapped around the rock and anchored to the surrounding ledge to arrest the movement. Photo credit Jon White.

A precarious rock above Manitou Springs started to move in 1995 after a period of wet weather. As an emergency measure, high-strength steel cables were wrapped around the rock and anchored to the surrounding ledge to arrest the movement. Photo credit Jon White.

The extremely unstable, tilted, rock could not be removed due to the proximity of homes directly below, so high-strength steel cables were wrapped around the rock and anchored to the surrounding ledge. Once the block was safely restrained, additional cables were physically attached to the top of the block at anchor points that were cemented into drill holes to provide an additional level of support for the block and safety for the homes below.

After the rock was stabilized, additional cables were physically attached to the top of the rock block and secured to surrounding stable rock. Photo credit Jon White.

After the rock was stabilized, additional cables were physically attached to the top of the rock block and secured to surrounding stable rock. Photo credit Jon White.

Jan 112017
 

Regarding the Colorado Geological Survey (an article appearing in the Mining Reporter, March 1907):

We note that one of our contemporaries, in recently commenting on the University bill creating a State Geological Survey of Colorado — the bill reported favorably on by the joint Senate and House mining committee — voices in no uncertain language its regret at the “truly pitiable outcome of the effort to establish a Geological Survey of Colorado.” In a lengthy and well-written editorial, criticism is made of the proposed advisory board, particularly of the placing thereon of the presidents of the State University and the State Agricultural College; also, having the survey located at Boulder instead of Denver; of the naming as state geologist, the professor of geology of the State University, who may be a good teacher, but who, like the majority, may or may not be an effective executive; and lastly, of the paltry appropriation of $5,000 annually for this important work in a state productive of $50,000,000 and more yearly.

Exception is also taken to the naming of state institution teachers as assistants to the State Geologist, who ought to have the assistance of men less academic and having a knowledge of the exploitation of ore deposits and of the search for them.

This editorial expression, coming from a former Coloradoan, is worthy of consideration. It is in accord, in large part, with our own views, as our readers know. In addition to the criticisms made by our contemporary, we would like to emphasize another objectionable feature in this favorably reported bill, viz., the naming of any one as state geologist who is not to devote his entire time to the survey work. — from the Mining Reporter, vol. LV, March 28, 1907, no. 13, Denver, Colorado.

We’re happy to say that our current efforts to provide professional geologic information to the residents of Colorado far exceed the original scope of responsibilities and possibilities of the Territorial Geologist. But like those old-time miners, walking the mountains of this beautiful state, we also share a real passion for what we are doing.

You can find an in-depth history of the Survey and its 1872-legislated precursor, the office of Territorial Geologist, in IS-27 History of The Colorado Geological Survey (1872-1988), a free PDF download at our bookstore.


Citation: Rold, J. W., and S. D. Schwochow. IS-27 History of The Colorado Geological Survey (1872-1988). Information Series, IS-27. Denver, CO: Colorado Geological Survey, Department of Natural Resources, 1989.
Sep 262001
 

CGS Special Publication 43, SP-43 A Guide to Swelling Soils for Colorado Homebuyers and Homeowners, by Dave Noe, William “Pat” Rogers, and Candace Jochim, is the winner of the 2001 Edward B. Burwell, Jr. Award by the Geological Society of America, Engineering Geology Division.

This prestigious award is made to the author(s) of a published paper of distinction that advances the principles or practices of Engineering Geology. Many of the previous award-winning publications have become hallmark references for the Engineering Geology and Geotechnical Engineering professions. Edward B. Burwell, Jr. was one of the founders of the GSA Engineering Geology Division, and was the first chief geologist of the U.S. Army Corps of Engineers. Continue reading »