Protozoic Metamorphic Rocks
Most of the metamorphic rocks in Colorado are Proterozoic in age. That means that they were heated and re-crystallized between 2,500 million years ago and 544 million years ago. Most of the metamorphic rocks were recrystallized between 1,800 million years ago and 1,300 million years ago.
Map below shows distribution ofProterozoic metamorphic rocks in Colorado.