The alluvium forms narrow floodplains and underlies terraces. At least
one well-developed terrace is present along the principal streams of
The alluvium yields more than 100 gallons per day to most dug wells.
Where sandy material is present and saturated thickness is great enough,
the alluvium yields more than 500 gallons per day to screened drilled
Breathitt Group (Pbl, Pbm) (Four Corners Formation, Hyden Formation,
The Breathitt Group underlies the valleys and forms the hills. Tops
of hills and ridges
commonly are capped by sandstone. Shales form wide valleys and moderate
or gentle slopes on
The Breathitt yields more than 500 gallons per day to almost half of the wells
drilled in valley bottoms
and more than 100 gallons per day to about half the wells drilled on hillsides
and on ridges. 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.
Grundy, Alvy Creek Formations (contains Lee-type quartzose sandstones
of the former Lee Formation) (Plc, Plr). Along Pine Mountain (PMl)
Thick, resistant sandstones in the Grundy form the high ridges along
Pine Mountain and underlie
an extensive upland in eastern Whitley County.
Generally, the Grundy yields more the 500 gallons per day to about three-quarters
of the wells drilled in
valley bottoms and lowland areas bordering streams and on hillsides.
About half the wells on
hilltops yield more than 500 gallons per day. Wells in small upland areas are
usually inadequate, with
production levels less than 100 gallons per day. Sandstone is the principal
aquifer, but shale yields water
to some wells and coal to a few. Joints and openings along bedding plains,
best developed in
sandstones, supply most of the water to wells. Waters are generally
soft or moderately hard and
contain noticeable amounts of iron.
Pennington Group (PDpg)
The Pennington forms moderate slopes along the face of Pine Mountain.
Hard beds of sandstones within this predominantly shale formation form
small cliffs or ledges.
The Pennington yields little or no water to wells.
Slade Formation (PDpg)
The Slade forms steep slopes and cliffs along the face of Pine Mountain.
The Slade yields more than 500 gallons per day to almost all the wells
drilled in valley bottoms, and to many wells drilled on hills. It yields
little water where overlain by Pennsylvanian rocks. Water is chiefly
from solution cavities in limestone, but sandstone and shale yield water
from fractures to a few wells. The Slade may contain salty water at
shallow depths. It yields as much as 50 or 100 gallons per minute to
springs in limestone.
Grainger Formation (PDpg)
The Grainger forms moderate slopes along the front of Pine Mountain.
The Grainger may yield more than 500 gallons per day to wells near the foot
of Pine Mountain, but wells
drilled into the formation throughout most of its outcrop area will
yield little or no water.
Chattanooga Shale (MDc)
The shale forms moderate slopes along the base of Pine Mountain.
The Chattanooga yields little or no water to wells.
The U.S. Geological Survey's Hydrologic
Atlas Series, published cooperatively with the Kentucky Geological
Survey, provides hydrologic information for the entire state.
to "Groundwater Resources in Kentucky"