Alluvium forms narrow floodplains and underlies terraces. At least one
well-developed terrace is present along each principal stream 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, more
than 500 gallons per day would be yielded to screened drilled wells.
Water is soft or moderately hard, and may contain large amounts of iron
Breathitt Group (Princess Formation, Four Corners Formation, Hyden
Formation, Pikeville Formation) (Pbm, Pbl)
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 planes 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) (PM1)
Thick, resistant sandstones form the high ridges of Pine, Cumberland,
and Rocky Face Mountains.
These formations generally yield more than 500 gallons per day to about
three-quarters of the wells drilled in valley bottoms. They yield 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 planes, 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.
These rocks yield 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. The formation
yields little water where overlain by Pennsylvanian rocks, but 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. A few wells at shallow depth may contain
salty water. The formation 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"