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Alluvium (Qa)
Topography
The alluvium forms terraces and narrow flood plains of varying width
along streams. At least one well-developed terrace is generally present.
Hydrology
Probably will yield as much as 20 or 25 gal/min to wells drilled and
screened in the alluvium of the Big Sandy River and its Tug and Levisa
Forks.
Breathitt Group (Pbu, Pbm, Pbl) / Conemaugh Formation (Pmc) (Princess
Formation, Four
Corners Formation, Hyden Formation, Pikeville Formation)
Topography
Sandstone forms narrow valleys and cliffs or steep slopes on hillsides,
and shale forms wide valleys and moderate or gentle slopes on hills.
Tops of hills and ridges commonly are capped by sandstone.
Hydrology
These formations yield more than 500 gal/day to most of the wells drilled
in valley bottoms and half of the wells on hillsides, and smaller quantities
of water to wells on hilltops. Most common aquifers are sandstone and
shale, but coal supplies water to a few wells. Near-vertical joints
and openings along bedding plains yield most of the water to wells.
Waters are highly variable in chemical character. May contain salty
water at depths less than 100 feet below the principal valley bottoms.
Grundy Formation (contains Lee type sandstone of the former Lee
Formation) (Plc)
Topography
Resistant sandstone beds two to three feet thick in the Grundy form
steep-sided, rounded hills and ridges.
Hydrology
The Grundy yields more than 500 gal/day to most wells drilled in valley
bottoms and to half the wells drilled on hillsides. 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. Inter-granular openings
yield water to joints, and probably directly to some wells. Perched
and semi-perched water tables are common. Yields moderately hard water,
and sometimes contain noticeable amounts of iron. In some places, may
yield salty water to wells drilled below drainage level.
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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