 The city and nearby smaller communities — Castanea , Dunnstown , Flemington , and Mill Hall — are mainly at valley level in the Ridge @-@ and @-@ Valley <unk> , a mountain belt characterized by long even valleys running between long continuous ridges . Bald Eagle Mountain , one of these ridges , runs parallel to Bald Eagle Creek on the south side of the city . <unk> of the confluence with Bald Eagle Creek , the West Branch Susquehanna River drains part of the Allegheny Plateau , a region of dissected <unk> ( also called the " Deep <unk> Section " ) generally north of the city . The geologic formations in the southeastern part of the city are mostly limestone , while those to the north and west consist mostly of <unk> and shale . Large parts of the city are flat , but slopes rise to the west , and very steep slopes are found along the river , on the university campus , and along Pennsylvania Route 120 as it approaches U.S. Route 220 . 
