358 UNIVERSITY OP VIRGINIA PUBLICATIONS 



beginning in order with those nearest Harper's Ferry and thence working 

 backward (southwest) throughout the length of the Shenandoah Valley, 

 capturing one stream after another. On the contrary the early stages of 

 the process resulted in the development of three drainage systems for 

 the entire region. These were, named in order from north to south, the 

 Potomac ; Goose Creek, adopted for the stream that once occupied Manas- 

 gas Gap; and Rockfish named for the stream that once occupied Rockfish 

 Gap. The relative importance of wind gaps, including size, depth, and 

 number, in the Blue Ridge, affords evidence that there was an inter- 

 mediate stage between the original condition of drainage and this triple 

 system ifi which there was probably a larger number of smaller systems, 

 but the evident ultimate result was the three systems mentioned above. 

 The drainage of the region at this period as it is conceived to have been 

 is shoMTi in figure 4. 



The larger of the two sj^stems south of the Potomac was Goose Creek 

 which left the Valley province through Manassas Gap opposite Front 

 Royal (pi. V, fig. 2). The presence of Massanutten Mountain which 

 rises as an additional barrier in a part of the Valley drained by this 

 system enables us to solve much of the history with ease and reasonable 

 accuracy. 



In the Cretaceous cycle. Goose Creek was one of many streams that 

 flowed across the Valley and the Blue Ridge in antecedent courses. Being 

 more able bodied than neighboring streams it lowered its channel across 

 the Blue Ridge barrier faster than the others resulting in its tributaries 

 capturing all the smaller streams in its vicinity, both to the northeast 

 and southwest. 



The capture of North Fork by tributaries of Goose Creek affords the 

 most interesting case of piracy in the region, and also shows the details 

 of the process by which the various antecedent streams have been inter- 

 cepted at a number of points in their courses before adjustment was 

 complete. As stated above North Fork entered the Valley through Brock's 

 Gap opposite Broadway and flowed across the Vallej^ through New Market 

 Gap (pi. Ill, fig. 1), in Massanutten ^Mountain, and thence across Page Val- 

 lej'', and the Blue Ridge through Thornton's Gap. A tributary of Goose 

 Creek first intercepted North Forjc on the east side of jMassanutten Mountain 

 near Lura}^; abandoning its com'se through Thornton's Gap it continued 

 across Massanutten Mountain for a long period through New Market 

 Gap. Another tributary of Goose Creek headed west of Massanutten 

 Mountain wdth its course through Moreland's Gap in the most westerly 

 ridge of the range, and following Little Fort Valley entered Goose Creek 



