THE SUGAR LOAF ARKOSB. 355 



Offshore the rock is well but coarsely bedded; cross-bedding and 

 coarse ri])pling- are often well marked; bands of comminuted coaly matter 

 from rotted and disintegrated wood occur; but all signs of abandonment 

 by the water, as mud-cracks, tracks, etc., are wanting. It occupies a broad 

 band commencing at the north end and running down the west side of 

 the valley, and expands to occupy the full width of the valley centrally 

 across nearly the whole of Hampshire County. South of Mount Hol^oke 

 it branches, and across Hampden County occupies the east and west sides 

 of the basin in broad bands. 



CONTACT AND DISTRIBUTION. 



Along the western side of the valley the contact of the shore beds 

 and the schists is first seen in Bernardston, in the brook gulch just south of 

 the Devonian limestone, and in the same pasture. Here there is a thin 

 remnant of the conglomerate resting on the basset edges of the Devonian 

 quartzite and mica-schist, and it is made up of a coarse red sandstone, full 

 of large angular fragments of the rocks on which it rests. There is here 

 scarcely more than a single layer of pebbles cemented to the edges of the 

 schist. 



On Fox Brook south of the road over West Mountain, in Bernards- 

 ton, the very coarse arkose can be seen almost in contact with the schists, 

 showing that almost from the beginning the strong northward tidal currents 

 can-led their granitic material even into this far northern portion of the 

 basin. Skirting the base of the great argillite block of Leyden, south 

 and west, the contact is everywhere covered until Leyden Glen, in the 

 northwest corner of Greenfield, is reached. Here is a brook gorge of great 

 natural beauty, affording an opportunitv to study the extreme contortion of 

 the argillite, as well as to see the contact of the Triassic beds upon the 

 latter, the whole dissected out most beautifully by the erosion of three 

 brooks. Just below the dam of a burnt mill, on the east side of the main 

 brook, a small stream comes down over the argillite, here flat-bedded, with 

 strike N. 10° E., dip 90°, and has cut through a basal stratum of the Trias, 

 which is plastered against the argillite, the plane of contact dipping 45°. 

 The stratum is here made up of subangular masses, nearly an inch across, 

 of the vein quartz derived from the argillite, and is quite uncemented. It 

 is 1 to 1 J inches thick, and passes gradually up into a bed, 2 or 3 inches 



