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Alluvium (Qa)
Topography
The alluvium forms narrow, discontinuous floodplains and small terraces
along the larger streams.
Hydrology
The alluvium generally is inadequate for a domestic supply, being too
thin and too fine-grained to yield much water. Water is hard.
Ste. Genevieve Limestone (Mgl)
Topography
The Ste. Genevieve underlies dissected karst areas in uplands, and forms
steep slopes on hills in Casey County.
Hydrology
Wells that do not intersect karst conduits generally are inadequate
for domestic use. Springs having low flows ranging from less than 10
gallons per minute to more than 200 gallons per minute occur at or near
stream level or near the contact with the underlying St. Louis Limestone.
St. Louis Limestone (Mgl)
Topography
The St. Louis's thick limestone beds form ledges and cliffs. Resistant
siltstone and nonresistant shale layers form discontinuous minor benches
on hillsides.
Hydrology
The St. Louis yields more than 50 gallons per minute to wells from large
openings in karst areas. Most wells penetrate some solution openings,
but where openings are small, yields are inadequate for a domestic supply.
A major spring horizon occurs near the top of the formation in the karst
areas. Many seepage springs occur throughout the formation; low flows
range from less than 10 gallons per minute to more than 500 gallons
per minute. The lower part of the formation is composed of siltstone
and argillaceous limestone. Yields from these sedimentary rocks are
low and generally are not adequate for a domestic supply with a bailer
or bucket.
Salem and Warsaw Formations (Msh)
Topography
These formations underlie moderately to highly dissected rolling uplands.
In some areas, numerous small sinkholes occur in the Warsaw.
Hydrology
These rocks yield enough water for a domestic supply where the formations
are dominantly limestone, but yields are low where siltstone or argillaceous
limestone is penetrated. A minor spring horizon occurs at the contact
of the limestone with the underlying siltstone or argillaceous limestone.
Another spring horizon occurs near the contact of the Warsaw and Fort
Payne. Low flows generally are less than 5 gallons per minute.
Fort Payne Formation (Mbf)
Topography
The Fort Payne underlies moderately to highly dissected rolling uplands.
It forms “knobs” and a major escarpment in Casey County, where
it is modified by faults. It forms steep bluffs along rivers.
Hydrology
Wells in lowland areas close to streams produce enough water for a domestic
supply. Most wells obtain water from perched or semiperched water bodies
supported by discontinuous shale layers, and many are dry during late
summer and fall. Minor spring horizons occur throughout the formation.
Flows are as much as 30 gallons per minute, but most go dry in late
summer or fall. Where the formation consists predominantly of siltstone,
most wells are inadequate for domestic use (less than 100 gallons per
day). Where the Fort Payne chert crops out in lowland areas close to
streams, the limestone and chert facies supply enough water for a domestic
supply.
Borden Formation (MDbb)
Topography
The Borden forms the main part of the Mississippian escarpment, ridges,
and knobs. The shale forms dissected slopes, massive siltstone forms
cliffs, and limestone forms ledges on shale slopes.
Hydrology
The Borden yields 100 to 500 gallons per day to wells in valley bottoms.
It may yield more than 500 gallons per day to drilled wells in broad
valley bottoms from fractured sandy rocks near streams, but almost no
water to wells on hills. Water from wells drilled below stream level
may contain salt, sulfate, or iron less than 100 feet below the level
of the principal valley bottoms. Water from dug wells and small springs
is soft and has a low dissolved-solids content. Water from shale is
soft; from the siltstone, hard; and from the limestone, very hard. Because
much of this formation is soft and silty, it has been well suited to
the construction of dug wells in the past, which generally produce less
than 500 gallons per day and often go dry in late summer and fall. The
New Providence Shale yields little or no water to wells.
New Albany Shale (MDnb)
Topography
The shale forms steep slopes near the base of the eastern mountain margin
escarpment and knobs. It underlies small round hills near the base of
the escarpment and broad flat valleys along major streams.
Hydrology
The shale generally yields little or no water to wells. Water is hard
and may contain large amounts of hydrogen sulfide and iron. Small springs
are present at numerous horizons, but most go dry during late summer
and fall. A few wells in eastern Casey County have produced as much
as 0.5 gallon per minute.
Boyle Dolomite (MDnb)
Topography
The Boyle forms resistant ledges on valley sides between shale slopes
above and below.
Hydrology
The dolomite yields almost no water to drilled wells, but yields water
to many small perennial springs. Water is hard but otherwise of good
quality.
Drakes Formation (Od), (Odc)
Topography
The Drakes forms dissected upland areas with moderately steep slopes
where underlain by shale, and moderately undulating to gently rolling
where underlain by limestone. It forms steep and cliffy slopes along
large streams, littered with limestone slabs left as shale beds weather
and wash away.
Hydrology
The Drakes yields 100 to 500 gallons per day to drilled wells in broad
valleys and along streams in uplands, but yields almost no water to
drilled wells on hillsides or ridgetops. It does yield water to small
springs. Water is hard and in valley bottoms may contain salt or hydrogen
sulfide. Shale limits the amount of water that has access to thick limestone
beds, and therefore restricts the number of openings in these beds enlarged
by solution. As a result, the limestone beds yield little water.
Ashlock Formation and Calloway Creek Limestone (Oaf)
Topography
These formations create gently to moderately rolling uplands away from
major streams, more highly dissected where shale content increases.
Small sinkholes, minor underground drainage, and broad, flat valleys
occur where limestone predominates. The lower part forms broad, flat
ridges between steep-sided valleys cut into underlying shale.
Hydrology
These formations yield 100 to 500 gallons per day to drilled wells in
broad valleys and along streams in uplands, but almost no water to drilled
wells on hillsides or ridgetops. They do yield water to small springs.
Water is hard and in valley bottoms may contain salt or hydrogen sulfide.
Where thick limestone beds with little shale occur below stream level
in valley bottoms or on uplands, they may have undergone solutional
enlargement of fractures and bedding-plane openings. Wells drilled into
these limestone beds may produce more than 500 gallons per day. These
thick beds also yield water to some large springs.
Cumberland Formation, Leipers Limestone, Catheys Formation (Ocl)
Topography
These limestone layers, interbedded with shales, form discontinuous
ledges along hillsides in some areas.
Hydrology
In lowland areas bordering large streams, these rocks yield enough water
for a domestic supply (more than 500 gallons per day). Elsewhere they
yield little water to wells and small quantities of water to springs.
Deep wells generally yield sulfurous water or brines.
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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