What type of elevation does Allegheny Front and Appalachian Platea have in common?
Allegheny Front The Allegheny Front is the major southeast- or east-facing escarpment in the Allegheny Mountains in southern Pennsylvania, western Maryland, and eastern West Virginia, USA. The Allegheny Front forms the boundary between the Ridge-and-Valley Appalachians to its east and the Appalachian Plateau (locally called the Allegheny Plateau) to its west. The Front is closely associated with the Appalachian Mountains' Eastern Continental Divide, which in this area divides the waters of the Ohio/Mississippi river system, flowing to the Gulf of Mexico, from rivers flowing into Chesapeake Bay and from there into the Atlantic Ocean.
Allegheny River Lock and Dam No. 4 The Allegheny River Lock and Dam No. 4 in Harrison Township, Allegheny County, Pennsylvania, is a lock that was built 1920-1927, and opened in 1927, 24.2 miles upstream from the mouth of the river in Pittsburgh. The lock and dam were built by the U.S. Army Corps of Engineers as a part of an extensive system of locks and dams to improve navigation along the Allegheny River. It has a single lock and a fixed crest dam, keeping the river depth at least 9 feet in the pool above the dam. The amount of water that flows over the dam is not controlled locally, so it does not provide flood control, but it does help provide water to municipalities.