PHYSICAL GEOGRAPHY OF THE COUNTY. F\ 27 



ranged straight lines, that these are pretty sure to cut across 

 the outcrops of the formations. But the difficulty of de- 

 scribing a "valley " is equally great ; for what the geologist 

 calls a valley is not in all cases what the inhabitants of it 

 will accept. 



Sometimes indeed the geological valley coincides with 

 the course of the stream through which it flows ; as in the 

 case of Raccoon valley, Little Buffalo valley, Hunter's Run 

 cove, and Allen's cove in the eastern part of Perry county, 

 Horse valley, Little Illinois valley, and Houston's valley 

 in the western part, and Shaeffer valley and Kennedy Run 

 valley in the south. 



In other cases the geological valley is occupied by several 

 streams, sometimes flowing in opposite directions ; as in the 

 case of Fishing Creek valley, one half of which is drained 

 eastward into the Susquehanna at Marysville, the other by 

 a branch of Sherman's creek westward to Shermansdale ; 

 and in the case of Liverpool valley, one half of which is 

 drained by Barger's run eastward, and the other half by 

 Wild Cat run westward. 



Even Little Buffalo Creek valley has its western part 

 drained in an opposite direction (westward) by Buffalo creek ; 

 and Raccoon valley has its western third drained by branches 

 of Sherman's creek ; and Little Juniata Creek valley has its 

 western end drained (westward) by another branch of Sher- 

 man's creek. 



Sherman's valley is a notable instance of the looseness 

 with which the term "valley" is applied in geography, as 

 opposed to the strictness with which the term must be used 

 in descriptive geology. For, by "Sherman's valley" is 

 popularly understood not only the open country from Sher- 

 mansdale to Duncannon through which the lower part of 

 this line stream meanders, but also the open country from 

 Bridgeport all the way to the west end of the county through 

 which the stream flows in its middle and upper courses. 

 But these two open countries have wholly different geolog- 

 ical characters, and are separated entirely from one another 

 by a ridge, through which the stream breaks, leaving the 

 one and entering the other ; that is, forsaking one geological 



