344 NEW YORK STATE MUSEUM 



liirc'l, lu'vcrtliclcss llic liciicnil dii-cd ion of ilicsc niicicnt streams 

 (Mil Itc iiidicnlcd willi ;i I'nii- ;i|i]»i();i(li \{> accnrncy. Davis^ has 

 iiidicahMl some ol' llic jn-olmldc di-;iiii;im' lines of lliis early period 

 ill the rciiiisyJNjniia ic^ioii and liis ;issiiiii|il ions may Ix' iv^ardetl 

 as ('.\|ir('ssino llu* conditions (d' llnil lime as accnralely as the 

 jtrcseni evidence will perniil. After I lie loi'ination of tlie Aj)j)a- 

 hudiian folds, tiien nmcli more in-ononnced than now. llie syn- 

 clinal Nalleys were oecni)ied by lon<»itiidinal (•oiise<]iient streiinis, 

 which drained into hikes filling the 1ow(M' basin-shaped depressions 

 between the ridges. Some of these were drained northwest^^ard 

 by the master stream of the region which l>a\is has named the 

 Anthracite river and whicli lie locates not tar from the present 

 Snsqnehanna. This river joined the ancient Ohio, which then as 

 noAV drained westward to the ]\Iississippi gnlf. Other small 

 streams flowed from the northwestern faces of the ^' Xittany high- 

 land " and the " Bedford range " and likewise became tribntary 

 to the Ohio. 



A feature which greatly complicated the drainage development 

 during Mesozoic time and in fact entirely changed the normal 

 conditions in the southwestern part of this area, was the folding 

 of the strata into the Appalachian anticlines and synclines which 

 took place during late Permian time, and the magnitude and 

 extent of which may be judged of by an examination of the 

 remnants found at present in the folded district. From the west- 

 ernmost slopes of these mountains, the drainage flowed north- 

 westward, but the drainage of the other slopes was carried along 

 the synclinal troughs and thus the inttn-ior was deprived of this 

 drainage, together with that of the Old A])])alachian continent to 

 the southeast. In consequence the streams flowing northwest 

 from this newly formed mountain area were much smaller than 

 those cohiing from the northeast, for the latter continued to carry 

 the drainage of a large i)art of the Oanadian old land into the 

 Mississipjd end)ayment. As a result the erosion in the north- 

 easteiai i-egion must have been mnch nioi-e ])ronounced, even 



'Davis, Willinui ^lorris. The Rivers and Valleys of Pennsylvania. Nat. 

 Geog. Mag. v. 1, no. 3. 



