Geologic Map of Colorado

_{U.S. Geological Survey map (fair use policy)}

Colorado packs an enormous range of geology within its four border lines. The Great Plains lie on the east, the Colorado Plateau on the west, the San Juan Volcanic Field 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.

This map was compiled in 1979 by Ogden Tweto of the U.S. Geological Survey and is a classic of geologic mapmaking. It 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

Back to Geologic Maps of the States