The geometry of this photo may be confusing: the rocks here on the north side of the roadcut are actually dipping east, toward the right. The oldest rocks are on the left. Visible in this photo, from left to right, are the mixed sedimentary rocks of the Morrison Formation (of Jurassic age, roughly 150 million years) and four members of the Dakota Group (of Cretaceous age, 140 to 100 Ma): the gray sandstone of the Lytle Formation, the lighter-colored Plainview Sandstone, the dark Skull Creek Shale, and at the very edge the Muddy or "J" Sandstone. They formed in various environments, on land and in shallow seas, along the shore of the Interior Seaway that once covered today's Great Plains.
The rocks dip into the ground and continue eastward as part of the Denver basin, where some of the units are sources of oil and gas.
Local geologists from the Colorado Geological Society saw a great opportunity when this roadcut was made. On the north side of I-70, interpretive signs explain the different rock units. Similar signs on the south side have been removed or destroyed by vandals. The Point of Geological Interest is therefore an ideal place to establish an Earthcache, a special kind of geocache used for teaching science without disturbing public lands.