Yazoo Clay
Geologic formation in the United States
From Wikipedia, the free encyclopedia
The Yazoo Clay is a late Eocene clay geologic formation in Alabama, Louisiana, and Mississippi. It was named after a bluff along the Yazoo River at Yazoo City, Mississippi.[1] It contains is a type of clay known as montmorillonite, making it a poor foundation material due to the fact that moisture causes extreme changes in volume. Sand, pyrite, and marl have all been noted in the formation. It preserves fossils including the prehistoric cetaceans Basilosaurus and Zygorhiza, and the marine snake Pterosphenus.[1][2] Sharks, rays, eels, and fish have also been found from the formation.[3]
TypeFormation
Unit ofJackson Group
Sub-unitsNorth Twistwood Creek Member, Cocoa Sand Member, Pachuta Marl Member, and Shubuta Member
UnderliesCrystal River Formation
| Yazoo Clay | |
|---|---|
| Stratigraphic range: Late Eocene | |
| Type | Formation |
| Unit of | Jackson Group |
| Sub-units | North Twistwood Creek Member, Cocoa Sand Member, Pachuta Marl Member, and Shubuta Member |
| Underlies | Crystal River Formation |
| Overlies | Moodys Branch Formation |
| Lithology | |
| Primary | clay |
| Other | sand, marl |
| Location | |
| Region | Alabama, Louisiana, Mississippi |
| Country | United States |
| Type section | |
| Named for | Yazoo River |
