|
Alluvium (Qa), Glacial Sediments (Qg)
Topography
These sediments form floodplains and terraces of the Ohio and Licking
River Valleys. Highest terraces are about 100 feet above normal pool
level of the Ohio River. Floodplains and terraces are along tributaries.
The sediments are too thin in tributary valleys to have distinctive
topography.
Hydrology
The sediments yield moderate to large quantities of water to drilled
wells in the Ohio River Valley, depending on thickness and texture of
the valley fill and type of well. The Ohio River alluvium yields 200
to 500 gallons per minute to ordinary tubular wells and as much as 1,000
gallons per minute to gravel-packed wells. Yields are more than 3 million
gallons per day during the summer in the Covington-Newport area of the
valley. The sediments yield little water from fine-grained material.
Small to moderate amounts of water are yielded to drilled wells in the
Licking River Valley; most wells yield more than 500 gallons per day.
Water is hard and near the valley walls of the Ohio and Licking Rivers
may have a high iron content. Wells that penetrate the alluvium and
enter bedrock obtain little additional water, and this water may contain
objectionable amounts of salt or hydrogen sulfide.
High-Level Fluvial Deposits (QTf)
Topography
These deposits lie at the top of low hills near the Licking and North
Fork Licking Rivers.
Hydrology
The deposits yield 100 to 500 gallons per day to drilled wells that
penetrate thick sandy parts of the channel fill of cemented conglomerate
and interlayered sand. Water is moderately hard. Glacial sand on uplands
yields soft water to small springs and dug wells. In most areas away
from the Ohio River, these deposits are generally too thin and scattered
to be important as an aquifer.
Grant Lake Limestone / Fairview Formation (Oaf)
Topography
These formations create gently to moderately rolling uplands away from
major streams such as the Ohio and Licking Rivers. They form moderately
dissected uplands where shale content increases, and steep, dissected
slopes along large streams. Ledges of thick limestone beds occur on
steep hillsides and bluffs along streams. Streams in uplands produce
broad, flat valleys where thick limestone beds are present, and may
have small sinkholes with minor underground drainage. Low hills on uplands
also may be capped by thick limestone beds of the Grant Lake and Fairview
formations. The lower part forms broad, flat ridges between steep-sided
valleys cut into the underlying shale of the Kope Formation.
Hydrology
These formations yield 100 to 500 gallons per day to drilled wells in
valley bottoms and along streams on uplands. They yield more than 500
gallons per day from thick limestone beds in broad valley bottoms. They
yield almost no water to wells on hillsides or hilltops, but may yield
some water to dug wells on ridgetops. They do yield water to small springs.
Small perennial springs occur in the lower Grant Lake Limestone. Water
is hard and in valley bottoms may contain salt or hydrogen sulfide.
The relatively impermeable shale prevents circulation of large quantities
of groundwater in joints and bedding-plane openings of relatively soluble
underlying limestone. As a result, the limestone beds have few solutionally
enlarged openings, and little water is available to wells and springs.
Near the base of the Grant Lake, however, there is 25 feet or more of
limestone with small amounts of shale (Bellevue limestone member). Where
this limestone occurs at and below stream level in valley bottoms or
along streams on the uplands, fractures and bedding-plane openings have
been enlarged by solution; many small springs flow from outcrops, and
some drilled wells along streams yield more than 500 gallons per day.
Kope Formation (Ok)
Topography
The Kope forms rugged, much dissected topography of long, narrow, steep-sided
ridges and narrow, winding, V-shaped valleys with dendritic drainage
pattern. Steep slopes are littered with thin limestone slabs that remain
as shale erodes and washes away. The contrast with less rugged upland
surfaces of adjacent areas is marked except near major streams, where
change is masked by dissection.
Hydrology
The Kope yields 100 to 500 gallons per day to drilled wells in valley
bottoms along large streams, but almost no water to drilled wells on
hillsides or ridgetops. The Kope yields water to small springs and seeps.
It yields little water from a well-cemented sandy zone near the top
in Pendleton County. Water is hard in valley bottoms and may contain
salt or hydrogen sulfide. Shale units have small, poorly connected openings
that allow passage of only small quantities of water, restricting yields
to wells and springs and preventing recharge to underlying rocks. The
few thick limestone beds may yield water to small springs. On ridgetops,
shale impedes downward percolation of water and supports water in the
lower part of the soil and in a weathered-rock zone just beneath the
soil. High up on the sides of many ridges is a zone of seeps and small
springs; where the Grant Lake caps the ridges, the zone is generally
near or at the contact with the Kope Formation. Drilled wells on these
ridges obtain a little water at the contact between soil and bedrock,
but rarely at greater depths; if water is found at depth, it is mainly
in small quantities and of poor quality. Dug wells, with large wall
areas, are better suited for obtaining water from these bodies of water;
however, many go dry in late summer and fall.
Clays Ferry Formation and Its Point Pleasant Tongue (Okc)
Topography
The Clays Ferry lies in broad, flat valley bottoms along large streams
between steep, narrow ridges. Limestone has undergone solution and in
some areas is characterized by small sinkholes and subsurface drainage.
Smaller streams develop long, narrow, winding, V-shaped valleys similar
to those of the Kope Formation.
Hydrology
The Clays Ferry yields more than 500 gallons per day to wells drilled
in valley bottoms, and small amounts of water to wells on hillsides
and hilltops. It yields water to small springs. Water is hard or very
hard and may contain salt or hydrogen sulfide, particularly in wells
in valley bottoms; both, especially hydrogen sulfide, may be found in
wells on hillsides. Beneath broad interstream areas, much solutional
enlargement of fractures and bedding-plane openings has taken place
in the soluble zones beneath tributary streams, and many drilled wells
produce 100 to 500 gallons per day. Some wide, flat areas have small
sinkholes and some underground drainage.
Lexington Limestone (Tanglewood Limestone, Grier, Logana Members)
(Ol)
Topography
The Lexington lies in flat valley bottoms along the Licking River.
Hydrology
The Lexington yields more than 500 gallons per day to wells and as much as 150
gallons per minute in places.
Water is hard and may contain salt or hydrogen sulfide in some places.
High Bridge Group (Ohb)
Topography
The High Bridge has no surface exposure in this quadrangle, but underlies
the entire area.
Hydrology
The High Bridge is not likely to yield usable amounts for any use. It
is not considered an aquifer in this area.
Knox Group (Okx)
Topography
The Knox has no surface exposure in Kentucky, but underlies the state
at varying depths.
Hydrology
In central Kentucky, fresh water has been found in the upper 100 to
250 feet of this largely untested dolomite-rich aquifer. Wells often
exceed 750 feet in total depth, and high concentrations of dissolved
solids are found in many areas. Average reported yields range in the
10 to 20 gallons per minute range but as high as 75 gallons per minute.
You can find out more about the Knox
aquifer.
The U.S. Geological Survey's Hydrologic Atlas Series, published cooperatively
with the
Kentucky Geological Survey, provides hydrologic information for the
entire state. Atlases
covering the county are: HA-15,
HA-94.
Previous--Next--Back
to "Groundwater Resources in Kentucky"
|