Colorado Geologic Map

The Great Plains lie on the east, the Colorado Plateau on the west, the San Juan Volcanic Field with its circular calderas in the south-center marking the northern end of the Rio Grande Rift, and running in a wide band down the middle is the Rocky Mountains. This complex zone of multiple folding and uplift exposes rocks of the ancient North American craton while cradling Cenozoic lake beds full of delicate fossil fish, plants, and insects.

Once a mining superpower, Colorado is now a major destination for tourism and recreation as well as agriculture. It's also a powerful draw for geologists of all kinds, who gather by the thousands in Denver every three years for the Geological Society of America's national meeting.

I have also prepared a scan of a very large and much more detailed geologic map of Colorado compiled in 1979 by Ogden Tweto of the U.S. Geological Survey, a classic of geologic mapmaking. The paper copy measures about 150 by 200 centimeters and is at 1:500,000 scale. Unfortunately it is so detailed that it's of little use at anything less than full size, in which all place names and formation labels are legible. I've built full-size versions for each quarter of the state as follows:

Northwest quarter (3 MB)
Northeast quarter (2.6 MB)
Southeast quarter (2.8 MB)
Southwest quarter (3 MB)

All four are 2600x2200 pixels. They overlap slightly so that if you were a maniac, you could print out the four pieces and paste them together into the 5100x4250 master scan. You'll also need the explanation sheet (2000x3100 pixels, 1.7 MB) to identify all the formations shown.

More about Colorado Geology

More Colorado resources on About.com:
About Denver
Colorado Maps
Colorado Scenic Roads
Colorado Geography, State Symbols & Facts
Colorado Travel
Colorado Campgrounds
Colorado's Fourteeners
Colorado Rock Climbing
Colorado Resorts & Spas
Colorado National Parks
Colorado Archaeology