Denver Formation

The Denver Formation rests on the Arapahoe Formation, and its base is marked by the first appearance of tuffaceous sediments. It is overlain by the Dawson Arkose. In 2002 the Denver Formation was included as part of a larger unconformity-bounded unit named the D1 sequence, in order to facilitate basin-wide studies and avoid confusion arising from the lateral and vertical facies changes that occur within the Denver Basin. The base of the D1 is marked by the abrupt facies change at the top of the Laramie Formation, and its top is placed at the base of a regional paleosol series. The Arapahoe Formation and the Dawson Arkose are also included in the D1 Sequence. == Thickness and lithology ==

.The Denver Formation consists of alluvial fan, fluvial, and paludal deposits that accumulated at the foot of the growing Rocky Mountain Front Ranges. It ranges in thickness from to in the central part of the Denver Basin. It is characterized by significant amounts of andesitic volcanic debris, Several early Paleocene lava flows are present in the upper part of the Denver Formation at North and South Table Mountain near Golden, Colorado. The Ralston Dike, a body of intrusive monzonite located several miles to the northwest, probably represents the volcanic vent from which the flows erupted. Generally referred to as basaltic, they are classified either as monzonite (the lowest flow) and latite (the upper two flows), == Age and paleontology ==

The Denver Formation spans the Cretaceous-Paleogene boundary. The lava flows in the upper part of the formation are about 62 to 64 million years old according to radiometric dating, Plant fossils and remains of vertebrates, including turtles and mammals, are found throughout the Denver Formation. Dinosaur remains are restricted to the lower, Late Cretaceous, part. == Vertebrate paleofauna ==

Based on the Paleobiology Database except where noted: Ray-finned fish Amphibians Reptiles Squamates Turtles Crocodylomorphs Dinosaurs The Denver Formation's dinosaur fauna appears to share close similarities with those of other Maastrichtian-aged formations in western North America. However, the dinosaur remains in the Denver Formation are significantly more disarticulated and fragmentary, suggesting that the formation's depositional environment was not conducive to the rapid burial that would have preserved articulated dinosaur skeletons.'''' This formation represents the first known discoveries to science of Triceratops (a partial cranium with horns) and Tyrannosaurus (a tooth), as well as the type locality for another well-known dinosaur, Ornithomimus.'''' Ornithischians Saurischians Mammals Multituberculates Metatherians Cimolestans Placentals Former "condylarths". == See also ==