Kansas, US

Paleontology and geology

The Precambrian: The only Precambrian rocks in Kansas consist of subsurface bedrock that underlies the entire state. No fossils are known from these rocks. The Paleozoic: The Early Paleozoic (Cambrian through Devonian) in Kansas is represented only in drill cores that provide evidence of a shallow sea. The Late Paleozoic (Carboniferous and Permian), in contrast, is well represented by surface rocks. Sea level rose and fell repeatedly during the Carboniferous, and great swamps formed along the shores. Amphibians and early reptiles flourished in the swamps, along with the ferns, scale trees (Lycophyta), and other plants that provided the organic material that would eventually become coal. A diversity of marine invertebrates thrived in the warm, shallow seas. During the Permian, the climate became much drier and shallow seas were restricted to central Kansas. The harsh Permian climate did not support a rich diversity of life, but rare fossils of lungfish, sharks, and fish have been found. The Mesozoic:The Mesozoic is represented in Kansas primarily by Cretaceous rocks. Fossils of plants and marine invertebrates provide evidence that a shallow, warm sea covered the western part of the state at this time. Later in the Cretaceous, the sea deepened and sharks, mosasaurs, plesiosaurs, turtles, fish, and numerous invertebrates flourished. The Cenozoic: Most Tertiary rocks in Kansas were formed by the activity of streams carrying sediment eroding off the Rockies to the west and filling wide, shallow valleys, creating a broad plain. The climate was wetter and milder than today and the landscape was savanna-like. In the Quaternary, vast glaciers spread over the northeastern part of the state for a short time. Fine silt, ground from rock by the glaciers, was blown over much of Kansas to form loess deposits. Sand dunes piled up in the south central and southwest parts of the state. Coniferous forests, grassland savannas, and short grass prairies spread. Mammals such as mammoths, mastodons, camels, and saber-toothed cats, were common.