The Denver basin is one of the largest basins in the Rocky Mountain area. It extends across parts of Colorado, Nebraska, and Wyoming. The basin is typically asymmetric with its axis parallel with and close to the mountain front. The deepest part of the basin lies near Denver where there are more than 13,000 feet of sediments.

Strata in and around the basin indicate that the area was predominantly a marine shelf during the early Paleozoic. Uplift during the middle Paleozoic locally exposed older sedimentary rocks to extensive erosion.

Early Pennsylvanian seas transgressed the eroded Mississippian from the south. Fine to medium clastics and dense thin-bedded carbonates were deposited in these seas. The first major uplift of the Ancestral Rockies occurred near the end of the Atoka. This uplift reached its peak during the Des Moines. Clastic material from the uplifted mountains intertongues with marine sediments of the expanding Des Moines sea. Marine transgression continued through the Missouri and was followed by a slow regression during the Virgil. Regression continued during the Permian and a suite of rocks was deposited which range from normal marine through evaporitic to terrestrial.

Upper Permian and Triassic rocks indicate that the Ancestral Rockies were weakly positive and supplied sediments to a shallow hypersaline sea. Non-deposition persisted from Late Triassic to Middle Jurassic time. During the Middle and Late Jurassic, seas encroached from the northwest. At the close of the Jurassic, the seas regressed and a broad flood plain was developed.

The present basin form began to emerge as Early Cretaceous seas advanced from the north and south. Earlier sediments were reworked and the Jurassic-Cretaceous boundary was obscured. As the sea regressed fluviatile material from the east and northeast developed a complex delta system which intertongued with marine sediments basinward. Another delta extended into the area from the southwest and merged with an eastern delta. A second cycle of transgression and regression developed similar depositional patterns. Within these two Cretaceous sedimentary cycles significant reserves of oil and gas have been discovered. During the Late Cretaceous, a major transgression joined the northern and southern seas into a large seaway across the downwarping basin.

Laramide tectonic activity reached its peak during the Eocene. It was during the Laramide that the Front Range was uplifted and the basin acquired its present configuration.