Geologic units in Tipton county, Tennessee

Jackson (?) Formation (Tertiary) at surface, covers 0.6 % of this area: Jackson (?) Formation - Sand, with layers of gray clay, silt, and lignite. Exposed only in bluffs along Mississippi River; thickness at least 60 feet.
Lithology: sand; clay or mud; silt; lignite
Alluvial deposits (Quaternary) at surface, covers 26 % of this area: Alluvial Deposits - 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.
Lithology: sand; silt; clay or mud; gravel
High-level alluvial deposits (Quaternary-Tertiary) at surface, covers < 0.1 % of this area: High-level Alluvial Deposits - Iron-stained gravel, sand, silt, and clay; variable in thickness but generally less then 60 feet thick.
Lithology: gravel; sand; silt; clay or mud
Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers 0.7 % 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.
Lithology: alluvium
Loess (Quaternary) at surface, covers 69 % of this area: Loess - 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.)
Lithology: silt