"Pine Mountain looms in the distance....Over part of the timbered, craggy ridge extends the Trail of the Lonesome Pine. The northern flank of the mountain, blanketed with dense stands of timber, hems in the country as far the eye can see. The road, beginning its winding ascent of the mountain, follows a shelf below high overhangs of limestone. During the climb small mountain cabins are seen clinging to sloping side far below, looking like doll houses in the distance...."
-1939 WPA Guide to Kentucky, describing a trip from Jenkins to Cumberland

The nature of Pine Mountain is directly related to the nature of the oceans that covered this region hundreds of millions of years ago, and the processes that occurred after the oceans receded. Between 400 and 300 million years ago, the rock that became the Cumberland Mountains was laid in thick layers of sediments that accumulated during thousands of cycles of flooding by oceans. The small fragments of dead sea life became limestones, accumulations of sand became sandstones, and plant life compressed into coal.

After the oceans finally disappeared, the rocks began to move from regional land movements that began roughly 230 million years ago. Faulting (discontinuous movement between two rock masses) occurred along northwestern edge of Pine Mountain and produced the 125-mile long linear structure we observe today. The same movement produced Black Mountain and Cumberland Mountain to the south.

The faulting displaced the northwest base of Pine Mountain approximately 2,000 feet higher than land immediately to the north. This movement also titled the rock layers on Pine Mountain so that they "dip" down to the southwest at about 40 degrees. Erosion since this movement has lowered the height of Pine Mountain 1,000 feet and removed most of the coal seams that are so numerous in the surrounding mountains.

Most people wonder how rocks can move, warp, and dip...well they do so very slowly. The layers of rock that we walk on, and believe to be rigid, are actually quite flexible over large areas and are always moving. When rock layers experience great movement, such as on Pine Mountain, they fracture, or break apart, and speed the forces of erosion in the area of the fracture. Simply stated, fractures and faults both help destroy rock by exposing more surface area of the rock to the natural elements. Also, different types of rock erode at different speeds, and this process is called differential erosion.

The unique rock outcroppings observed along Pine Mountain, such as Raven Rock and the serrated pattern of hogbacks that run along the southeastern face of the mountain, result from this trio of forces: faulting, fracturing, and differential erosion.

The dry gaps (gaps or passes in mountains that contain no streams) on Pine Mountain, such as Hurricane Gap, were once believed to have been cut by streams while Pine Mountain was moving upward. At some point the stream could not cut down faster than the upward movement, so the streams were diverted to their present-day network.

A modern theory holds that the dry gaps were produced (and are still being produced) by erosion of small faults that cross along the Mountain. Faults have been mapped at Pound Gap and the Narrows Gap at Pineville. The fault at Narrows Gap, called the Rocky Face Fault, extends south to Cumberland Mountain producing the Cumberland Gap. Had this fault not created two lined-up gaps through two formidable mountains, the pattern of Kentucky's early settlement might be different than it is today.

Sources:
McGrain, Preston, "Scenic Geology of Pine Mountain in Kentucky." Kentucky Geological Survey.

Chesnut, Donald, Kentucky Geologic Survey. Interview June 27, 2000.