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The date of the impact coincides precisely with the Cretaceous–Paleogene boundary (K–Pg boundary), slightly more than 66 million years ago. [7] The crater is estimated to be over 150 km (93 mi) in diameter [10] and 20 km (12 mi) in depth, well into the continental crust of the region of about 10–30 km (6.2–18.6 mi) depth.
Plant fossils are common in both the Late Cretaceous and early Paleocene portions of the Edmonton Group. [7] Remains of Triceratops and other dinosaurs are found in the Late Cretaceous portion, especially the Horseshoe Canyon Formation and the lower part of the Scollard Formation. Molluscs such as Ostrea and Unio are found in both portions. [1]
Because the Raton Formation is a well-preserved sequence of rocks spanning the Cretaceous-Paleogene boundary, it has been studied for evidence of a large meteor impact at the end of the Cretaceous that is thought to have caused the Cretaceous–Paleogene extinction event. The boundary is represented by a 1-cm thick tonstein clay layer which has ...
The Cretaceous-Paleogene boundary occurs in the lower part of the formation, and an exposure of the boundary layer has been identified and documented on South Table Mountain near the city of Golden. [12] Plant fossils [13] and remains of vertebrates, including turtles [14] and mammals, [15] are found throughout the Denver Formation. [6]
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out, widely thought to have been caused by the impact of a large asteroid that formed the Chicxulub crater in the Gulf of Mexico.
The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary extinction event) [a] occurred at the end of this age. [3] In this mass extinction , many commonly recognized groups such as non-avian dinosaurs , plesiosaurs and mosasaurs , as well as many other lesser-known groups, died out.
In 1980, a team of researchers consisting of Nobel Prize-winning physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Michel discovered that sedimentary layers found all over the world at the Cretaceous–Paleogene boundary contain a concentration of iridium many times greater than normal (30, 160, and ...
The Cretaceous–Paleogene boundary, a major prehistoric global extinction event. During the Cretaceous period of late Mesozoic Era and Paleogene period of the early Cenozoic Era, in the Phanerozoic Eon.