The alluvium forms narrow flood plains and underlies terraces. At least
one well-developed terrace is present along the principal streams of
The alluvium yields more than 100 gal/day to most dug wells. Where sandy
material is present, and saturated thickness great enough, the alluvium
may yield more than 500 gal/day to screened drilled wells. Water is
soft or moderately hard; may contain large amounts of iron at depth.
Breathitt Group (Pbu, Pbm, Pbl) (Princess Formation, Four Corners
Formation, Pikeville Formation)
The Breathitt Group underlies the valleys and forms the hills of almost
all the area north of Pine Mountain. South of Pine Mountain the rocks
underlie the narrow valleys and form high, rugged hills. Tops of hills
and ridges commonly are capped by sandstone. Shales form wide valleys
and moderate or gentle slopes on hills.
The Breathitt yields more than 500 gal/day to more than three-quarters
of the wells drilled in valley bottoms. Throughout this area the Breathitt
yields of more than 500 gal/day to about three quarters of the wells
on hillsides and more than 100 gal/day to nearly all wells 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
Thick, resistant sandstones in the Grundy form the high ridges of Pine
The Grundy yields more the 500 gal/day to about three-quarters of the
wells drilled in valley bottoms, and more than 500 gal/day to about
half of the wells on hillsides. Smaller quantities of water are produced
by wells on hilltops. Some wells flow. 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 predominately 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 gal/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 depth in
a few wells. Yields from the Slade are as much as 50 or 100 gal/min
to springs in limestone.
Grainger Formation (PDpg)
Forms moderate slopes along front of Pine Mountain.
May yield more than 500 gal/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 base of Pine Mountain.
The shale 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"