Hydrogeologic Framework and Simulation of Ground-Water Flow and Travel Time in the Shallow Aquifer System in the Area of Naval Support Activity Memphis, Millington, Tennessee 

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Quaternary

Holocene 
and 

Alluvium 
(alluvial deposits)

0 - 70

Silt, clay, sand, and gravel. Underlies the alluvial plains of Big Creek Drainage Canal and tributary streams. A lower sand and gravel is connected to the fluvial deposits and constitutes part of the alluvial-fluvial deposits aquifer.

Pleistocene

Loess

15 - 45

Silt, clay, and sand. Principal unit at the surface in upland areas. Generally forms the upper confining unit for the alluvial-fluvial deposits aquifer. Locally contains perched water tables.

Quaternary 
and 
Tertiary(?)

Pleistocene 
and 

Fluvial deposits 
(terrace deposits)

5 - 70

Sand and gravel; minor clay and ferruginous sandstone. Thickness varies greatly because of erosional surfaces at top and base. Constitutes part of the alluvial-fluvial deposits aquifer.

Tertiary

Eocene

Claiborne

Cockfield Formation

0 - 185

Sand, silt, clay, and lignite. Complexly interbedded and interlensed. Preserved thickness varies greatly because of erosional surfaces at top and base. Locally contains sand lenses in which domestic and farm wells are completed. 

Cook Mountain 
Formation

10 - 60

Clay, silt, and sand. Generally consists of clay and silt. Locally serves as part of the lower confining unit for the Cockfield aquifer, and is the principal upper confining unit for the Memphis aquifer.

Memphis Sand

865 - 880

Sand, silt, clay, and minor lignite. Constitutes the Memphis aquifer--the principal aquifer providing water for most domestic, commercial, industrial, and municipal supplies in the Memphis area.