A valley is a relatively large hollow or depression bounded by hills or mountains on Earth's surface that is developed by stream erosion or glacial activity and that is drained externally. A basin is another hollow or depression on Earth's surface, but it has no outlet to drain the water.
Location in Allegheny County and the state of Pennsylvania. Gibsonia is an unincorporated community and census-designated place in Richland Township, Allegheny County, in the U.S. state of Pennsylvania, north of the city of Pittsburgh. It had a population of 2,733 at the 2010 Census. Its ZIP code is 15044.
Perry County Thumbnail. Perry County (1820), originally part of Cumberland County, is located in the south central section of Pennsylvania and consists of 564 square miles. It is composed of twenty-one townships and nine boroughs, of which Liverpool is one. It is bordered on the east by the Susquehenna River, the north by the Tuscarora Mountain, the south by the Blue Mountain, these two mountain ranges merge on the western edge of the county. The Juniata River crosses the county also.