Physioghraphy of Somerset County, Pennsylvania

    by Brian L. Fritz

Topography and Climate

Somerset County, Pennsylvania is located in "the Allegheny Mountain Section of the Appalachian Plateaus province" (Flint 1965:7).  The eastern boarder of the County loosely follows a topographic feature known as the Allegheny Front.  This feature marks the boundary between the tight folding of the Ridge and Valley province to the east and the less intensely folded Appalachian Plateaus province to the west.  "Probably the outstanding characteristic of the gross topography of the area is a parallelism of northeast-trending ridges" (Flint 1965:10).  At least one of five notable ridge lines will define the horizon from most any prominent vista.   The top of Laurel Mountain forms the western boarder of the County.   Located in the center  is Negro Mountain upon witch rests Mount Davis the highest point in Pennsylvania at 3,216 feet.  A south-east facing escarpment known as Allegheny Mountain runs the entire length of the County and forms the eastern boundary for the northern half.  Big Savage Mountain and Little Allegheny Mountain are found in the south-eastern corner.  The Little Allegheny Mountain together with the Allegheny Mountain form eastern boundary of both Somerset County and the Allegheny Mountains Section.

Somerset County occupies only a portion of the Allegheny Mountains Section which extends to the north, south, and west of it's boarders.  Past archaeological studies have referred to the Somerset County portion of the Allegheny Mountains Section as the "Somerset Plateau"  (George 1983:2).  This designation is particularly applicable to the area lying between Laurel Mountain and Allegheny Mountain where average elevations are generally higher than the adjacent regions both east and west of these two ridge lines.  Local residents will attest to the cooler climate associated with the higher elevations.  Snow cover usually occurs earlier and often remains longer with deeper more sustained accumulations.  This east west contrast has earned Somerset County  a reputation for having harsh winters.

Rivers and Watersheds

Topographical features in the eastern portions of Somerset County form a major watershed divide between the Ohio River that flows west to the Mississippi and the Gulf of Mexico, and the Susquehanna and Potomac Rivers that flow east to the Atlantic Ocean.  Four watersheds divide the county, the Stony Creek, the Casselman-Youghiogheny, the Wills Creek-Potomac, and the Raystown Branch of the Juniata.

Stony Creek River and it's tributaries drain the entire northern part lying between Laurel Mountain and Allegheny Mountain.  The headwaters begin near the center of the county and run due north.  Wells Creek, Beaver Dam Creek, Quemahoning Creek, Shade Creek, Paint Creek, and Bens Creek are the largest contributing streams.  Three miles north of the Somerset and Cambria County line the Stony Creek River joins with the Little Conemaugh River to form the Conemaugh River which eventually finds it's way to the Ohio via the Kiskiminetas and Allegheny Rivers.

In southern Somerset County the Casselman-Youghiogheny watershed drains all of the area west of Allegheny Mountain and a small area east of Allegheny Mountain in the south-eastern corner.  The Casselman River begins it's journey in Maryland flowing north into Somerset County were it turns west dissecting Negro Mountain, then flows south-west to a confluence with the Youghiogheny River and Laurel Hill Creek.  Contributing streams include Piney Creek and Flaugherty Creek with their headwaters beginning east of Allegheny Mountain, Blue Lick Creek, Buffalo Creek, Coxes Creek, Middle Creek, Whites Creek, and draining the eastern flank of Laurel Mountain Laurel Hill Creek.  The Youghiogheny River forms the county line in the most south-western corner starting from the Maryland-Pennsylvania line flowing north-west to where the river cuts through Laurel Mountain at Ohiopyle Gorge and eventually finding it's way to the Ohio via the Monogehela River.

The Raystown Branch of the Juniata River drains only a small portion of the County along the eastern slopes of Allegheny Mountain. It meanders it's way to the Atlantic Ocean through the Juniata River and  the Susquehanna River.  Wills Creek also drains eastern slopes of the Allegheny Mountain, flowing east through Savage and Little Allegheny Mountains.  Wills Creek joins with the North Branch of the Potomac River just south of the Pennsylvania Maryland boarder and flows eastward to the Atlantic.  The extreme south-eastern corner of the county drains directly to the North Branch of the Potomac River.


Flint, Norman K.
 1965 Geology and Mineral Resources of Southern Somerset County, Pennsylvania.
          Pennsylvania Geological Survey County Report C56A. Harrisburg.

George, Richard L.
 1983 The Gnagey Site and the Monongahela Occupation of the Somerset Plateau.
          Pennsylvania Archaeologist Vol. 53 No. 4.