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Alluvium and Glacial Outwash Sediments (Qa)
Topography
These sediments form flood plains, valley bottoms, and terraces of the
Mississippi River and tributaries. Valley-train deposits beneath terraces
along Mississippi River.
Hydrology
Yields from shallow driven wells in the Mississippi valley are adequate
for domestic use; however, near the river water levels fluctuate greatly
and some shallow wells are dry or are inadequate in the summer and fall.
Drilled wells in the Mississippi alluvium may supply large amounts of
water from the deeper, gravelly unit for irrigation and for public and
industrial uses, except in areas where the saturated thickness is less
than 10 feet. Saturated thickness generally ranges from about 30 to
150 feet and a well may yield 3,000 gal/min or more in favorable areas.
Yields of 1,000 gal/min may be expected in most places. The water is
hard and contains objectionable amounts of iron and manganese. Yields
several hundred gallons a minute to drilled wells in the alluvium of
the Cumberland and Tennessee River valleys. Yields enough water for
a modern domestic supply (more than 500 gal/day) to nearly all wells.
Yields practically no water to wells in small valleys where the alluvium
is thin and fine-grained. Water ranges in hardness from 12 to 664 ppm
and in dissolved solids from 53 to 1,220 ppm. Iron may be present in
objectionable amounts.
Loess
Topography
Loess forms a thin mantle over most uplands, and gently sloping sides
of stream valleys. Thick deposits occur adjacent to the Mississippi.
The loess forms steep bluffs where thick. Many badlands or heavily-eroded
gullies occur in the uplands.
Hydrology
The loess is not an aquifer. It yields small amounts of water to a few
wells. When saturated by rainfall, loess transmits water to underlying
aquifers.
Terrace Gravel Deposits and Continental Deposits (QTcl)
Topography
These deposits occur on uplands and eroded edges of uplands above 370
feet.
Hydrology
These deposits yield small quantities of water suitable for household
use. One spring had measured discharge of 47 gal/min. Most wells yield
less than 10 gal/min. Water-bearing gravel usually overlies clay or
indurated layers. Water ranges in hardness from 8 to 724 ppm and in
dissolved solids from 43 to 782 ppm. Iron content is generally low.
Jackson, Claiborne (Tjc)
Topography
These formations form uplands and high-level erosional surfaces. They
extends beneath river terraces along Mississippi valley.
Hydrology
Sand yields enough water for domestic use in areas of perched water.
Drilled wells penetrating main zone of saturation where beds are thick
yield as much as 1,700 gal/min. Hardness of water ranges from 7 to 212
ppm, and dissolved solids from 28 to 431 ppm. Iron may be present in
objectionable amounts.
The U.S. Geological Survey's Hydrologic
Atlas Series, published cooperatively with the Kentucky Geological
Survey, provides hydrologic information for the entire state.
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