north-easterly strike prevalent north-east of a line extending, 

 in a general way, from Boston, via the White Mountains, to 

 the northern end of Lake Champlain, would, if continued 

 south-westerly, carry the crystallines of New England over 

 New York, and the Middle States generally. But beyond the 

 line indicated the formations bend to the south, and through- 

 out south-western New England are characterized by approxi- 

 mately north and south strikes, being cut off at right angles 

 by the waters of Long Island Sound. Along the New York 

 boundary, in southern Connecticut, however, the north-east 

 strike is resumed, and the rocks of that district sweep across 

 Manhattan Island and the Hudson. The breadth of New 

 England strata subjected to this westerly deflection is prob- 

 ably not so great as at first sight appears. The crystallines 

 of the Highlands of the Hudson are Laurentian, and are rec- 

 ognized by all geologists as older than those farther south, in 

 the vicinity of New York. It is the latter only that can be 

 traced easterly into New England, or that are here considered 

 as really belonging to this great geological province. The 

 Laurentian strata of the Highlands have a north-north-east 

 strike, varying toward north and south ; and it is probable 

 that in their northerly extension, although soon dipping 

 beneath more recent formations, they sweep around to a 

 course parallel with the one hundred and fifty miles of newer 

 crystallines on the east, and reappear in Washington and 

 Saratoga Counties in New York ; thus connecting the Lauren- 

 tian of the Highlands and New Jersey on the south with the 

 great Adirondack area on the north, and constituting at all 

 points a barrier against which abut the western edges of the 

 crystalline series proper to New England. The complete 

 absence, so far as has been definitely ascertained, of Lauren- 

 tian rocks from western New England corroborates this 

 view. In short, the crystalline formations of the northern 

 half of the Atlantic seaboard exhibit, in their strikes, a 

 grand double curve. Beginning in the north-east with a 

 trend parallel with the St. Lawrence and the Laurentide 



