The world, Early Cretaceous (Aptian Age), 120 Ma, Global Paleogeographic Views of Earth History, NAU
The world, Early Cretaceous (Albian Age), 105 Ma, Global Paleogeographic Views of Earth History, NAU
The world, Late Cretaceous, 94 Ma, PALEOMAP Project
The world, Late Cretaceous (Turonian Age), 90 Ma, Global Paleogeographic Views of Earth History, NAU
The world, Late Cretaceous-Paleogene boundary, 66 Ma, PALEOMAP Project
North America, Early Cretaceous, 140 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Early Cretaceous, 130 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Early Cretaceous, 115 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Early-Late Cretaceous boundary, 100 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Late Cretaceous, 85 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Late Cretaceous, 75 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America, Late Cretaceous-Paleocene boundary, 65 Ma, Paleogeography and Geologic Evolution of North America, NAU
North America in the Cretaceous Period
North American Cretaceous Rocks (pale green)
Cretaceous, Palæos
Cretaceous, Wikipedia
The Cretaceous, Paleontology Portal
The Cretaceous, University of California Museum of Paleontology
Geologic Time Table, Seafriends
See general sources above.
Early Cretaceous, ~130 Ma, PALEOMAP project
Late Cretaceous, ~85 Ma, PALEOMAP project
Cretaceous: Life, Wikipedia
Chalk Group, Coccolith, Coccolithophore, Wikipedia
Cretaceous Period: Life, University of California Museum of Paleontology
The Cretaceous: Flowers Bloom For The First Time, Fossil-Facts-and-Finds.com
Cretaceous Fossils, Fossil Museum
Large rifts develop in West Gondwana between Africa and South America.
India and Madagascar separate from the rest of East Gondwana (Antarctica and Australia).
Rifting begins between Antarctica and Australia.
The separation of Gondwana forms huge undersea mountain chains and sea levels rise.
Mountain building (orogeny) that began in the Triassic and Jurassic periods continues to build active volcanic mountain ranges in western North America and South America (American Cordillera). This is caused by subduction of the Farallon and Kula Plates under western North America. The Sevier orogeny creates thrust faulting and lifting in sedimentary rock.
The rising mountains of the American Cordillera begin to form Mexico and Central America.
The North Atlantic Ocean and the Gulf of Mexico continue to grow due to spreading. North America completely separates from South America and a seaway develops between them allowing ocean currents to circulate.
The ocean floods North America, forming the Western Interior Seaway, and the Hudson Seaway. A third of the Earth's land area submerges under shallow seas.
Giant swamps form along the border of the Western Interior Seaway, which will become the Cretaceous coal deposits found west of the Rocky Mountains today.
Rifting separates Madagascar from India. India rapidly begins to move northward towards Asia.
A subduction zone develops in the northwest of North America as the Kula Plate moves north and sinks. Alaska begins to form.
The angle of the subduction of the Farallon plate becomes less steep. Volcanic mountain building on the margin of the continent slows and stops. Instead, volcanoes and mountain building occur farther east. The western part of North America, which had already been raised before in the Nevadan and Sevier orogenies, lifts again during the Laramide orogeny. The Rocky Mountains form, and continue raising into the Paleogene Period. Folding creates the Black Hills of South Dakota.
Numerous meteor impact events, especially near the end of the period, including:
Morokweng crater (Botswana. Jurassic-Cretaceous boundary), Gosses Bluff crater (Australia), Mjølnir crater (off the coast of Norway), Tookoonooka crater (Australia), Mien crater (Sweden), Rotmistrovka crater (Ukraine), BP Structure (Gebel Dalma) (Libya), Oasis crater, (Libya), Carswell crater (Canada), Mount Toondina crater (Australia), Sierra Madera crater (Texas), Deep Bay crater (Canada), Kentland crater (Indiana), Arak crater (Alaska), Steen River crater (Canada), Dellen crater (Sweden), Wetumpka crater (Alabama), Zeleny Gai crater (Ukraine), Manson crater (Pennsylvania), Lake Lappajärvi (Finland), Kara crater (Russia), Chukcha crater (Russia), Ouarkziz crater (Algeria), Tin Bider crater (Algeria), and Vargeão Dome (Brazil).
With four meteor impacts dating to near the Cretaceous-Paleogene boundary:
Boltysh crater (Ukraine), Eagle Butte crater (Canada), Vista Alegre crater (Brazil), and the Chicxulub crater impact event (Mexico) near the Cretaceous-Paleogene boundary. The Alvarez hypothesis says this last impact was the primary cause of the K-T extinction (see below).
One of the largest extinction events in earth's history occurs at the end of the Cretaceous, the K-T extinction. Dinosaurs, marine reptiles, and flying reptiles die out. There may have been multiple causes for the extinction including increased volcanic activity, falling sea levels, and multiple meteor impacts.
© 2009, Mr. Varner.
