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.
Irwin is a borough in Westmoreland County, Pennsylvania, 22 miles southeast of Pittsburgh. Some of the most extensive bituminous coal deposits in the State are located here. In the past, iron foundries, flour mills, car shops, facing and planing mills, electricals goods, and mirror factories provided employment to the residents. In 1900, the population numbered 2,452; it increased to 2,886 in 1910. The population was 3,973 at the 2010 census.