Hershey.] The Hirer Terraces of the Orleans Basin. 



42.") 



It has an altitude of nearly or quite 7,000 feet. A long, even- 

 crested ridge from 8 to 12 miles northwest of Orleans is another 

 undoubted remnant of the same peneplain. It constitutes the 

 divide between the Smith River drainage basin and that of the 

 Klamath, and extends far to the north on the line between Del 

 Norte and Siskiyou Counties. It seems to have a general altitude 

 of about 6,000 feet. 



The summit of Orleans Mountain, four miles east-southeast 

 from Orleans, although it is not flat, is approximately another 

 remnant of the Klamath peneplain. It has an altitude of about 

 6,500 feet. Orleans Mountain rises abruptly on the southeastern 

 border of the Orleans Basin, so that we have here a range in alti- 

 tude of about 6,000 feet in less than three miles. East of the 

 Klamath River and north of the Salmon River abundant rem- 

 nants of the peneplain have altitudes no less than 7,000 feet. It is 

 thus evident that the Klamath peneplain in the Orleans region 

 is due at 6,000 to 7,000 feet above sea level, and its level at 

 Orleans may be given at 6,500 feet. 



The Sherwood Valley of the Klamath Eiver is not well defined 

 in this region, but there are sufficient evidences to approxi- 

 mately fix the level at which its floor is due at Orleans. Appar- 

 ent remnants of this floor occur northeast of the basin, near the 

 mouth of Salmon Eiver, at altitudes of 4,000 to 4,200 feet, and 

 southwest from the basin at similar altitudes. The Sherwood 

 valleys of the Klamath region appear to have been characterized 

 by long, gentle, curved slopes leading from the neighboring 

 mountains to the flat central portion. The valley over the Or- 

 leans Basin appears to have had a width of ten or twelve miles, 

 although the flat portion was perhaps only a third as much. The 

 depth in the center was 2,500 feet. 



The Sierran canon of the Klamath River is a profound trench, 

 comparable in width and depth with the great Sierra Nevada 

 canons. Between the mouth of the Salmon River and the mouth 

 of the Trinity River, a distance of twenty miles, it is 3,500 feet 

 deep. It does not have the true canon form, as the walls are not 

 straight and precipitous, so that it is hardly proper to write of 

 its "brink." The rocks of the region have been extensively 

 cracked to great depth, and consecpiently will not stand in mural 



