Geologic units in Obion county, Tennessee

Additional scientific data in this geographic area

Loess (Quaternary) at surface, covers 74 % of this area

Clayey and sandy silt, gray to brown, massive. Maximum thickness about 100 feet along bluffs of Mississippi River; thins eastward. (Minimum mapped thickness 4 feet.)

Alluvial deposits (Quaternary) at surface, covers 24 % of this area

Sand, silt, clay, and gravel. In flood plain of Mississippi River more than 100 feet thick; in smaller streams generally less than 20 feet thick.

Jackson (?) Formation (Tertiary) at surface, covers 0.9 % of this area

Sand, with layers of gray clay, silt, and lignite. Exposed only in bluffs along Mississippi River; thickness at least 60 feet.

Continental deposits and loess, undifferentiated (Tertiary to Quaternary) at surface, covers 0.5 % of this area

Continental deposits and loess, undifferentiated; West of the Tennessee River

High-level alluvial deposits (Quaternary-Tertiary) at surface, covers 0.4 % of this area

Iron-stained gravel, sand, silt, and clay; variable in thickness but generally less then 60 feet thick.

Alluvium (Pleistocene to Holocene) at surface, covers < 0.1 % of this area

Alluvium; includes glacial deposits along the Ohio River and its tributaries west of Cannelton locks

Jackson and Claiborne Formations, undivided (Tertiary) at surface, covers < 0.1 % of this area

Jackson and Claiborne Formations, undivided; includes some rocks of Oligocene age