Most visitors to Mesa Verde National Park go there to see the spectacular cliff dwellings that are preserved in the sandstone alcoves. But these sandstones and the entire landscape tell an interesting geologic story as well. It may be a stretch to say that if there were no cliff dwellings on Mesa Verde that visitors would still go there. But the view from the top of the mesa is world-class and a little knowledge of the rocks brings another learning dimension to the locality. In July of this year I made a geologic excursion to the park with colleague Jack Share.
Cretaceous age. As rocks fall off of the edge of this escarpment, it retreats slowly through time to the south (towards the left in this view). That means that these layers once extended up slope farther to the north (to the right) and onto the southern flank of the San Juan dome, a Laramide-age uplift present in southwest Colorado. The rate of retreat on this escarpment can likely be figured out using rates from nearby areas on the Colorado Plateau and may be on the order of about one meter every 2,000 years.
laccolith about 28 million years old. See my previous post on laccoliths in this area here.
point bar deposits from a stream meandering on a coastal plain, some 82 million years ago. As the Cretaceous Seaway retreated to the east, it exposed a low-lying plain that was coursed by many rivers. A map of Menefee time is provided two images down. The black layers are coal seams within the Menefee Formation.
here or purchase a copy of our book, "Ancient Landscapes of the Colorado Plateau" here.
is what led to the "discovery" of this entire ruin complex.