Breathitt Group (Pbu, Pbm, Pbl) (Princess Formation, Four Corners
Formation, Hyden 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 gallons per day to more than three-quarters
of the wells drilled in valley bottoms. Throughout this area it yields
more than 500 gallons per day to about three-quarters of the wells on
hillsides and more than 100 gallons per 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 Formation) (PMl)
The Grundy's thick, resistant sandstones form the high ridges of Pine,
Cumberland, and Rocky Face Mountains in Harlan County.
Generally, the Grundy yields more the 500 gallons per day to about three-quarters
of the wells drilled in valley bottoms. It yields more than 500 gallons
per day to about half of the wells on hillsides and smaller quantities
of water to 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)
This group 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. The Slade may yield more
than 400 gallons per minute to wells at Pineville. 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. 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 Chattanooga forms moderate slopes along the 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"