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Alluvium (Qa)
Topography
The alluvium underlies floodplains and terraces of all streams.
Hydrology
The alluvium may yield as much as 100 gallons per minute from sands
and gravel along the Green and Tradewater Rivers. The alluvium yields
enough water for a modern domestic supply (more than 500 gallons per
day) to wells in valleys of the Green and Tradewater Rivers and their
larger tributaries. It yields practically no water to wells in small
valleys, where it is thin and fine grained. Water is hard or very hard
and may contain objectionable amounts of iron.
Terrace gravel deposits (Qt)
Topography
These deposits underlie tops and flanks of hills between elevations
of 420 and 500 feet along the Green River.
Hydrology
In places, these deposits yield enough water for a domestic supply to
dug wells. Water generally is soft and low in dissolved solids content,
but may contain objectionable amounts of iron.
McLeansboro Group (Mattoon, Bond, Patoka, and Shelburn Formations),
formerly the Sturgis Formation (Ps)
Topography
This group forms dissected uplands and ridgetops.
Hydrology
This group yields practically no water, except to wells penetrating
sandstone. Water from shallow wells near outcrop areas is hard. Water
from deep wells farther from the outcrop area is generally soft and
contains sodium bicarbonate (in some places in objectionable amounts).
Iron may be present in objectionable amounts. The Anvil Rock Sandstone,
sometimes found at the base of the unit, may yield up to 125 gallons
per minute. In areas where the Kentucky No. 11 coal has been mined,
the sandstone may be dry, or it may yield water containing iron sulfate.
Carbondale Formation (Pc)
Topography
The Carbondale forms dissected uplands and ridgetops and underlies much
of the county.
Hydrology
The Carbondale yields enough water for a modern domestic supply to wells
penetrating sandstone, but practically no water to wells penetrating
only shale. Wells are known to produce as much as 30 gallons per minute.
Water is hard or very hard, but otherwise of good quality. The Carbondale
yields either no water or water containing iron sulfate in areas where
the Kentucky No. 9 coal has been mined.
Tradewater Formation (Pt)
Topography
The Tradewater underlies dissected uplands and ridgetops and most of
the county. Resistant
sandstone beds in the Tradewater form cliffs.
Hydrology
The Tradewater generally yields only small quantities of water to wells.
It may yield enough for a modern domestic supply to wells penetrating
a sufficient thickness of sandstone. Water is fresh near outcrop areas,
but becomes increasingly mineralized with depth.
Caseyville Formation (Pca)
Topography
The Caseyville underlies dissected and rolling uplands. Thick sandstone
beds in the Caseyville
form cliffs and a major escarpment.
Hydrology
The Caseyville will yield enough water for a modern domestic supply
to most wells penetrating
sandstone. Yields of 100 gallons per minute have been obtained from wells penetrating
thick sections of
sandstone. At depth, the water becomes salty or may have a high sodium
bicarbonate content.
Water is hard to very hard and low in dissolved solids. Wells in small
upland areas generally are
inadequate.
Generalized areas of underground mining have been compiled for several
important coal beds as part of the U.S. Geological Survey's National
Coal Assessment Program. Using this data, a map was created showing
mined-out
areas of selected beds in the county.
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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