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Alluvium (Qa), Glacial Sediments (Qg)
Topography
The alluvium forms flood plains and terraces of the Ohio and Licking
River valleys. Highest terraces are about 100 feet above normal pool
level of the Ohio River. Flood plains and terraces occur along tributaries.
The alluvium is too thin in tributary valleys to have distinctive topography.
Hydrology
These sediments yield moderate to large quantities of water to drilled
wells in the Ohio River valley, according to thickness and texture of
the valley fill and type of well, with yields 200 to 500 gpm (gallons
per minute) to ordinary tubular wells and as much as 1,000 gpm to gravelpacked
wells. Sediments yield more than 3 million gpd (gallons per day) during
the summer in the Covington-Newport area of the valley. Fine-grained
sediments yield little waterl. The sediments yield small to moderate
amounts of water to drilled wells in the Licking River valley, with
most wells producing more than 500 gpd. Water is hard and near the valley
walls of the Ohio and Licking 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.
Bull Fork Formation (Ob)
Topography
The Bull Fork forms gently to moderately rolling uplands where limestone
predominates; more dissected where shale predominates.
Hydrology
The Bull Fork yields 100 to 500 gpd to wells in valleys or on broad
ridges, but almost no water to drilled wells on narrow ridges or hilltops.
It does yield water to dug wells and to small springs. Water is hard
and of good quality.
Grant Lake Limestone / Fairview Formation (Oaf)
Topography
These rocks form gently to moderately rolling uplands away from major
streams such as the Ohio and Licking Rivers, and moderately-dissected
uplands where shale content increases. Steep, dissected slopes occur
along large streams, and ledges of thick limestone beds on steep hillsides
and bluffs along streams. Streams in uplands produce broad, flat valleys
and where thick limestone beds are present may have small sinkholes
with minor underground drainage. Low hills on uplands also may be capped
by thick limestone beds. The lower part forms broad, flat ridges between
steep-sided valleys cut into the underlying shale of the Kope Formation.
Hydrology
These rocks yield 100 to 500 gpd to drilled wells in valley bottoms
and along streams on upland, and more than 500 gpd 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 ground water 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. However, near the
base of the Grant Lake 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 gpd.
Kope Formation (Okc,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. 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 gpd to drilled wells in
valley bottoms along large streams, but
almost no water to drilled wells on hillsides or ridgetops. It does
yield water to small springs and seeps. Water is hard in valley bottoms
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 lower part of soil and in weathered-rock zone just beneath
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.
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-98.
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