TRIASSrC SHORE PHEXOMEXA. 453 



Where the exact boundary can be seen, as south of the Bernardston lime- 

 stone bed and at Leyden glen, a local conglomerate of quartz pebbles from 

 the schists rests on the crystalline rock ; but is only a few inches thick, and 

 in many places large, well rounded pebbles of vein quartz from the schists 

 appear in the arkose, carried out from the shore by the undertow and mingled 

 with the granitic material brought from farther southward. 



The Conglomerate. — A current of still greater force swept southward along 

 the eastern border of the valley, carrying much coarse material derived from 

 the peculiar schists which form the eastern plateau in Northfield, and form- 

 ing a conglomerate with blocks often two to four feet long and with every- 

 thing less than two inches long washed out of it. 



The boundary between these two deposits, the arkose and the coarse con- 

 glomerate, is a narrow band rather than a line, but can be followed very 

 sharply across Gill. It is the interlocking boundary of two contemporaneous 

 deposits shifted in vertical section from east to west as the two opposing cur- 

 rents varied in strength. 



Buried Peaks. — On following the coarse Mount Toby conglomerate further 

 southward into the mountain from which its name has been taken, a series 

 of very gratifying and surprising discoveries was made, which at once cleared 

 up the question of the origin of the problematical rocks and strengthened 

 the proof of the current system here being explained. 



At Whitmore's ferry, on the Connecticut at the northern line of Sunder- 

 land, fishes have long been found in the black Triassic shales. These occur 

 at the water's edge and dip eastward beneath Mount Toby, the place being 

 the western foot of the mountain in the center of the Triassic basin. In the 

 bluff just above, and in apparent conformity, appear fine-grained black rocks, 

 which are made difficult of access by the waters of a brook coming down over 

 them in a pretty waterfall. 



Examining these rocks at the top of the bluff and just south of the mill- 

 pond, on the edge of the latter, I was surprised to find three roches moutonees 

 of quartzite and hornblende schist rising in the midst of the conglomerate, 

 where I should have said the Triassic must be at least a thousand feet thick. 

 The ice-smoothed surface showed clearly that the schist was much jointed ; 

 a little south the blocks were slightly moved, then a little red sand was 

 filtered into the fissures, and then the blocks were gradually moved out of 

 place so that they could be only partly refitted, and soon foreign material 

 (granite and vein quartz) appeared as pebbles among the other constituents. 

 This was effected in three rods of fine ice-polished surface, and fragments 

 from these peculiar quartzites and hornblende schists appeared in the con- 

 glomerate in abundance for miles southward. 



A similar outcrop was found later on the northern spur of the high hill 

 that rises west of Montague. Here a peculiar porphyritic granite appears in 



