University of California . 



[Vol. 3. 



Smith Fork Valley, but I subsequently determined the fact that 

 the valley above is a remarkable V-shaped gorge, presenting no 

 evidence of glaciation. I am now satisfied that the deposit is 

 a landslide which came down the high mountain on the south- 

 cast and obstructed the valleys of the main Pearch Creek and 

 its South Fork. These streams have trenched it to depths 

 between 100 and 150 feet, the main creek with a valley several 

 hundred feet wide. Consequently, it is bounded on the creek- 

 ward sides by a steep bluff, above which it rises more gently to 

 perhaps 500 feet above the streams. The surface is covered with 

 coarse, angular fragments of rock, with a few scattered water- 

 worn cobbles. 



It is important to know the position with reference to Pearch 

 Creek of the bed-rock under this landslide. I could find no 

 rock exposures at the foot of the bank along the South Fork, 

 but the loose material appeared to go to the creek-level. On the 

 Pearch Creek side a later deposit intervenes between the old 

 landslide and the creek. However, it is practically certain that 

 the valley had been cut down to nearly or quite the present 

 stream-level before the landslide occurred. This limits its age 

 to comparatively recent times. Further, the erosion of canons 

 in it to depths of 100 to 150 feet seems to warrant its reference 

 to the time or about the time of the formation of the torrent 

 fans and landslides farther up Pearch Creek. 



It seems that Pearch Creek was subsequently interrupted 

 just above the mouth of the South Fork by a landslide from 

 the north side of the valley. This partly overrode a creek deposit 

 which is now exposed in a perpendicular bank, and partly incor- 

 porated the creek gravel into its mass, so that waterworn pebbles, 

 cobbles and boulders occur with the angular rock debris, 

 embedded in a reddish clay. The comparative recency of this 

 landslide is evident from the fact that Pearch Creek passes it 

 in a narrow gorge, instead of having a valley several hundred 

 feet wide, as above and below this point. 



Next, the creek passes a narrow belt of resistant Paleozoic 

 chert, where, although the floor of the valley is 100 to 150 feet 

 wide, the walls are steep and rocky and no terraces appear. 

 After this the stream enters on the relatively soft Bragdon slate, 



