532 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



mimitus. A sug-gestion of loug needles of lionibleude or chiastolite also 

 occurred. 



Or further examination the minute garnets on the surface were found to 

 be polished down and scratched like the rest. At one portion of the surface 

 unmistakable glacial striae were found adjoining the problematical grooves. 

 That the marks were formed by movement of an upper layer of the slate on 

 the underlying ledge seemed clear, and that the garnets fixed in the bottom 

 of the upper moving stratum furnished the grooving tools. The change 

 in the direction was caused by a change in the direction of the moving 

 mass, some portion of the bottom becoming fixed and forming a pivot 

 around which the rest revolved. That the mass was moved only a slight 

 distance from its original position was also clear. Whether this motion 

 was caused by glacial ice, by the expansion and contraction of the rock, 

 or by earthquake action, I can not decide. 



POT-lIOIiES. 



President Hitchcock notes ^ the absence of pot-holes among the results 

 of the diluvial currents which were supposed to have originated the till and 

 the glacial striae, and concludes therefrom that these phenomena were not 

 the work of rivers but of widespread currents without falls of much magni- 

 tude. He describes later a great series of pot-holes west of Shelburne Falls, 

 on the road to Charlemont, in an old l)ed of the Deerfield River, 85 feet 

 above the present stream, which may have belonged to a pre-Glacial bed of 

 the river or may be of Glacial age. 



Pot-holes occur, of course, along the channel of the Connecticut and 

 its tributaries, in the former especially below its falls in the canyon formed 

 by their recession, in the latter on the bottoms of the deep gorges they 

 have cut through the crystalline rocks. 



Striking illustrations are to be seen in tlie Westfield River, at the 

 Crescent Paper Mills, in the extreme north of Russell. Just below Russell 

 station also a great dike of granite formerly obstructed the stream, but has 

 been cut through, and here are many pot-holes. One interesting one was 

 half removed as the stream cut down its bed, and the remaining half is 

 still to be seen in the wall, about 10 feet above the water. It is regularly 

 um-shaped, with bent constricted neck, and is about 6 J feet deep. 



' Final Report. 1.S41, p. 392. 



