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Breathitt Group (Pbu, Pbm, Pbl) (Princess Formation, Four Corners
Formation, Hyden Formation, Pikeville Formation)
Topography
The topography 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. The tops of hills and ridges commonly are
capped by sandstone.
Hydrology
In most of Breathitt County this group yields more than 500 gallons
per day to most wells in valley bottoms. In the remainder of the area,
yields are more than 500 gallons per day to three-quarters of the wells
drilled in valley bottoms. Throughout this area these rocks yield 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 planes yield
most of the water to wells. Waters are highly variable in chemical character.
Salty water may be found at depths less than 100 feet below the principal
valley bottoms in most of Breathitt County.
Grundy Formation (contains Lee-type sandstone of the former Lee Formation)
(Plc)
Topography
The Grundy Formation is composed of thick, resistant sandstone.
Hydrology
The Grundy yields more than 500 gallons per day to most of the wells
drilled in valley bottoms, and more than 500 gallons per day to about
half of the wells on hillsides. Wells on hilltops produce smaller quantities
of water. Sandstone is the principal aquifer, but shale yields water
to some wells and coal to a few. Vertical joints and openings along
bedding planes, best developed in sandstones, supply most of the water
to wells. Intergranular openings yield water to joints and probably
directly to some wells. Perched and semiperched water tables are common.
Waters are soft to moderately hard, and sometimes 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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