CHAPTERXII. 



THE TRIAS. 

 TBTE coistst:cticut river sandstone.' 



The Connecticut River sandstones extend northward from the Sound, 

 with a width of about 20 miles across Connecticut and Massachusetts to 

 Northampton; there they contract to about 6 miles, and continue north 

 with this width to Bernardston, where they contract to a mile in width, and 

 soon end just north of the village of Northfield. 



Their western boundary is everywhere coincident with the foot of 

 the bluif of crystalline rocks bordering the valley, and the same is true 

 of the eastern border from the south line of the State northward to the 

 Belchertown ponds. In this — the larger portion of their boundar}- — the 

 sandstones never extended much beyond their present limits, and show 

 everywhere shore conglomerates resting against the schists and granites on 

 which they were deposited. 



In the remainder of the eastern boundary, from the ponds north to 

 Mount Toby, the boundary of the sandstones has been carried by erosion 

 far west from the old shore line — the line of the bluffs in Pelham bordering 

 the valley on the east. From Mount Toby to the north line of the State 

 the extremely coarse conglomerates which form the present eastern ^Jortion 

 of the Trias must represent quite accurately the original eastern shore line, 

 and the deep depression which now separates these bluffs of conglomerate 

 from the escarpment of gneiss that forms the true border of the valley may 

 have been in large part produced by the erosion of Paleozoic schists which 

 crop out from beneath the Trias and occupy the bottom of this depression. 

 This is the more probable since this coarse conglomerate is made up wholly 



'The name Newark was proposed by Prof. I. C. Russell in 1889 for the Triassic of the Atlantic 



Coast. Prof. C. H. Hitchcock supported the name "The Connecticut Sandstone Group" in Science, 



Vol. I, 1895, p. 74. 



351 



