Geologic units in Dyer county, Tennessee

Additional scientific data in this geographic area

Alluvial deposits (Quaternary) at surface, covers 51 % 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.

Loess (Quaternary) at surface, covers 48 % 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.)

Jackson (?) Formation (Tertiary) at surface, covers 0.6 % of this area

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

Holocene series (Quaternary-Holocene Series) at surface, covers 0.4 % of this area

Alluvium - clay, silt, sand, and gravel.

High-level alluvial deposits (Quaternary-Tertiary) at surface, covers 0.3 % of this area

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

Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (Holocene) at surface, covers < 0.1 % of this area

Alluvial deposits in major stream channels or in mappable meanders of major streams - Includes alluvial deposits in natural levees in some areas.