452 OSCAR H. HER SHE Y 



mentioned and hence just below the gorge, glacial debris is scat- 

 tered thinly over the slope to the summit of the ridge, fully 700 

 feet above the river and 250 feet above the Big Flat on the 

 opposite side of the ridge. There are some large granite 

 bowlders, but among the material of lesser size, serpentine is 

 conspicuously abundant. This I suppose to represent the last 

 or Wisconsin glacial stage, the material seemingly having fallen 

 from the ice spanning across the gorge. Serpentine occurs in 

 equal abundance in the Wisconsin drift in the broad valley above 

 the gorge. The serpentine is only proportionally abundant 

 among the finer material. Small bowlders and cobbles well- 

 smoothed represent the subglacial and the lower stratum of the 

 englacial drift. Among the large angular and subangular bowl- 

 ders which were superglacially carried, serpentine is rare in the 

 Wisconsin drift near the gorge, a fact which must be taken into 

 account in comparing this with the serpentine-bearing apparent 

 drift farther down Salmon River. 



Leading down the river for about a mile and a half from the 

 saw-mill, the north side of the valley has a more or less continu- 

 ous strip of glacial moraine material which shows a tendency to 

 form an imperfect terrace at a level between lOO and 200 feet 

 above the river, with a few scattered erratics higher on the 

 mountain slope. This terrace corresponds to that which we 

 have traced on the opposite side of the river. The depression 

 between seems to be a valley of erosion, several hundred feet 

 wide and containing the lower terrace which I have referred to 

 the last glacial stage. If this interpretation be correct, a longer 

 time of erosion separated the two glacial maxima stages than 

 has succeeded the close of the last. ' 



The glacial material forming the indistinct upper terrace on 

 the north of the valley, contains an occasional serpentine 

 bowlder, proving that it was formed by a glacier coming from 

 beyond the gorge, but so far I have failed to find within it ser- 

 pentine in nearly the abundance in which it occurs on the higher 

 slope just west of the gorge and in the supposed old glacial 

 deposit along the Spooner ditch. I am constrained to consider 

 it as representing neither the earliest nor the latest glacial stage 



