hershev.] The River Terraces of the Orleans Basin 



45!) 



It is apparent that the forty-five-foot terrace of the Orleans 

 Basin system, upon being traced up Pearch creek, soon loses its 

 individuality and merges with the Modern alluvium. The sev- 

 enty-foot terrace has representatives to a distance of over two 

 miles up the creek, and among them is the lower terrace near 

 the North Fork. The 120-foot terrace, with its characteristic 

 torrent fans and landslides, is represented in Pearch ( "reek Val- 

 ley by similar phenomena. This torrent-fan and landslide form- 

 ing period immediately succeeded the maximum extension of 

 the glacier in Pearch Creek Valley. Therefore, the 120-foot 

 terrace may be referred to the time of the "Intermediate Glacial 

 Stage." Because of the great gaps in the terraces along Pearch 

 Creek, this conclusion is not absolute, but later I will adduce 

 other evidences that the 120-foot terrace is of the same age as 

 the so-called Intermediate glacial deposits. It is out of the 

 question that the Klamath River has cut 100 feet into solid rock 

 since any part of the last, or Wisconsin, glacial stage, and hence 

 the glacial deposit in Pearch Creek Valley must be referred to 

 some older period. 



GENERAL DISCUSSION. 



Changes of Grade. — The present river is abnormally high 

 grade. According to the topographic map already mentioned, 

 it descends from 482 feet (altitude at low water) opposite Sandy 

 Bar to 467 feet just below the Ferris Mine, a distance of about 

 a mile and a half, and it maintains at least the rate of ten feet 

 fall per mile through the basin. It falls 1.300 feet from Happy 

 Camp to Orleans, a distance of sixty miles, or over twenty feet 

 per mile. It is said that it accomplishes 114 feet of this fall in 

 less than two miles, at the Ischapischa and Mackyarum Falls, 

 near the mouth of Salmon River. From Orleans to the mouth 

 a distance of sixty miles, it falls 475 feet, or nearly eight feet 

 per mile ; but much of this is accomplished in the first seventeen 

 miles to Weitchpec, in which section it may fall over fifteen feet 

 per mile. 



Its natural condition at all stages is that of a swift mountain 

 stream, abounding in rapids. In high floods it rises thirty feet 

 at Orleans, where the channel is wide, and 80 to 100 feet near 

 Weitchpec and Martin's Ferry, where it is in narrow rock 



