 The city and nearby smaller communities — Castanea , Dunnstown , Flemington , and Mill Hall — are mainly at valley level in the Ridge @-@ and @-@ Valley Appalachians , 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 . Upstream of the confluence with Bald Eagle Creek , the West Branch Susquehanna River drains part of the Allegheny Plateau , a region of dissected highlands ( also called the " Deep Valleys 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 siltstone 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 . 
 The city and nearby smaller communities — Castanea , Dunnstown , Flemington , and Mill Hall — are mainly at valley level in the Ridge @-@ and @-@ Valley Appalachians , 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 . Upstream of the confluence with Bald Eagle Creek , the West Branch Susquehanna River <a href='uninflect' title='1'><mark>drains</mark></a> part of the Allegheny Plateau , a region of dissected highlands ( also called the " Deep Valleys Section " ) generally north of the city . The geologic formations in the southeastern part of the city <a href='drop_aux' title='2'><mark>are</mark></a>mostly limestone , while those to the north and west consist mostly of siltstone and shale . Large parts of the city <a href='drop_aux' title='3'><mark>are</mark></a>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 <a href='uninflect' title='4'><mark>approaches</mark></a> U.S. Route 220 . 
Da city and nearby smaller communities — Castanea , Dunnstown , Flemington , and Mill Hall — are mainly at valley level in the Ridge @-@ and @-@ Valley Appalachians , a mountain belt characterized by long even valleys running between long continuous ridges . Bald Eagle Mountain , one of dese ridges , runs parallel to Bald Eagle Creek on tdasouth side of thdaity . Upstream of the confluence with Bald Eagle Creek , thedast Branch Susquehanna River drain part of the daegheny Plateau , a region of dissected highlands ( also called the " Deep Valleys Section " ) generally north of the city . The gdaogic formations in the sodaeastern part of the citdaostly limestone , while those to the nortdand west consist mostly of siltstone and shale . bigass parts of the city dat , but slopes rise to the west ,dad very steep slopes r found along the river , on the university campus , and along Pennsylvania Route 120 as it approach U.S. Route 220 .