MOUNT GREYLOCK. 193 



The interaction of all these have molded the mountain and given it 

 its varied topography. 



The physically and chemically more resistant schists form the more 

 elevated portions ; also the steeper and more rugged and wooded slopes, while 

 the broad, cultivated valleys of the Hoosic, Green, and Housatonic rivers, 

 and the mort > gei itly undulating portions of the mountain generally correspond 

 to limestone areas. The upper limestone strata and calcareous schists con- 

 stitute the benches of agricultural and pasture land, which form so marked a 

 feature in the Greylock landscape, and to which attention was directed in the 

 Introduction. Thus die Notch and the agricultural character of its surface 

 find their explanation partly in its anticlinal structure and partly in the cal- 

 careous element of its strata. The character of the bench on the east flank 

 of Ragged mountain has already been noticed. Similarly the broad bench, 

 which extends for 2 miles at an altitude of 2,000 to 2,500 feet above sea 

 level on the west side of the central ridge between Greylock and Saddle 

 Ball and around "Jones's Nose" (see Pis. xm, xiv), corresponds to the 

 gently inclined strata of Formation Sbp, with its easily weathering and 

 subsoil-forming micaceous limestone. This accounts for the farms which 

 once dotted its surface, still mostly recognizable as open pasture land. 

 Thus, also, is explained the incision between Round rocks and Saddle Ball. 

 (Fig. 74 and Section Q.) 



The 2£-mile long north to south extension of the great Hopper cut was 

 partly occasioned by the trend of the folds and partly by the upturned edges 

 of the calcareous belt, which, on the north, at "Wilbur's pasture," and, on 

 the south, at "Shattuck's flats," still retain something of their former surface 

 outline. (See PL xvn.) Prof. Dana's surmise that the north to south Hopper 

 depression is due to a subordinate anticline 1 is correct, but the anticline seems 

 to occur on the west side of the Hopper. The main east to west Hopper 

 incision does not seem to correspond to any structural feature, but to be 

 simply the result of the surface drainage of the west slope of the range eating 

 back, i. e.. eastward, through the subordinate folds until it reached the cal- 

 careous belt, and then, owing possibly in part to the sharpness and conse- 

 quent weakness of the anticline west of it, but mainly to the more assailable 



On the quartzite, limestone, etc., in the vicinity of Great Barrington, Massachusetts, p. 273. 

 MOW Will 13 



