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Alluvium (Qa)
Topography
The alluvium forms narrow floodplains and underlies terraces. At least
one well-developed terrace is present along the principal streams of
the region.
Hydrology
The alluvium yields more than 100 gallons per day to most dug wells.
Where sandy material is present and the saturated thickness is great
enough, the alluvium would yield more than 500 gallons per day to screened
drilled wells. Water is soft or moderately hard; it may contain large
amounts of iron at depth.
Breathitt Group (Pbu, Pbm, Pbl) (Princess Formation, Four Corners
Formation, Hyden
Formation, Pikeville Formation)
Topography
The topography of the Breathitt is rugged. Sandstones form narrow valleys
and cliffs or steep slopes on hillsides and shales form wide valleys
and moderate or gentle slopes on hills. Tops of hills and ridges commonly
are capped by sandstone.
Hydrology
In western Perry County, the Breathitt yields more than 500 gallons
per day to most wells in valley bottoms. In eastern Perry County, it
yields more than 500 gallons per day to three-quarters of the wells
drilled in valley bottoms. Throughout the county, the Breathitt yields
more than 500 gallons per day to almost half the wells on hillsides
and smaller quantities of water to wells on hilltops. Sandstones yield
water to most wells. Shales also yield water to many wells, and coal
yields water to a few. Near-vertical joints and openings along bedding
plains yield most of the water to wells. Waters are highly variable
in chemical character. Wells may contain salty water at depth.
Grundy Formation (contains Lee-type sandstones of the former Lee
Formation) (Plc)
Topography
The Grundy contains thick sandstones in the subsurface.
Hydrology
Generally, the Grundy yields more than 500 gallons per day to most of
the wells drilled in valley bottoms. It yields more than 500 gallons
per day to about half of the wells on hillsides and more than 500 gallons
per day to almost three-quarters of the wells on hilltops. Sandstone
is the principal aquifer, but shale yields water to some wells and coal
to a few. The highest yielding wells obtain water from near vertical
joints and openings along bedding plains. Intergranular pore spaces
yield water slowly to joints and to wells intersecting poorly cemented
zones. Waters are generally soft or moderately hard and contain noticeable
amounts of iron.
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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