MUSEUM OF COMrAKATIVE ZOOLOGY. 



269 



Reference to Percival's description of these ridges is given farther on. 

 Professor Dana gives a brief mention of the traps of this district {d, 46 ; 

 most of this article applies to the quatcrnarj features of New Haven). 

 E. S. Dana and Hawes describe the composition of the trap here and 

 elsewhere, and note an increase in the hydration and alteration of the 

 eastern traps over the western. (See below, under Composition of 

 Trap.) All of the trap is regarded as intrusive by these authors. 



From the descriptions given above, and a comparison of this region 

 with otlicrs, I am led to believe that the Saltonstall Ridge is an over- 

 flow : its small metamorphic effect at the base, its decided amygdaloidal 

 texture on the back or upper surface, its irregular and brecciated 

 structure, and its -alteration and hydration, all agree with the characters 

 of overflow sheets rather than with those of well proven intrusions, such 



as East Rock and the Palisades. 



Palisade Range. — H. Fort Lee and Englewood, N. J, — Sandstone 

 shows at the water's edge above and below the wharf at Fort Lee. 

 About eighty feet up the hill, under the Bluff Point House, a path cut- 

 ting shows baked shales seven feet from the trap * A two-mile walk 

 northward from hej-e leads one obliquely over the range toward Engle- 

 wood, showing many wclhglaciated knobs of coarse, dense trap on the 

 way ; the glacial stri£e advance obliquely up the back of the range, bear- 

 ing S. 20^^ E. 



Floraville, a mile south of Euglewood on the Triassic Map of New Jersey 

 (Cook, a), gives a good exposure of the iq)pcr contact of sandstone on 



trap.f 



The trap is of rather coarse texture when first shown in the stream ; 



it is evenly divided by parallel joints, one to three feet apart, dipping 



12° W. N. W., just as the sandstone dips farther on; the columnar 



structure is subordinate to this appearance of bedding. Followmg down 



the stream-bed, the texture soon becomes finer, but is nowhere vesicular, 



and in a short distance highly metamorphosed sandstones and shales are 



reached. Their bedding is very even, and not perceptibly disturbed 



near the trap ; their color varies from nearly black to gray or greenish ; 



in texture they are jaspery or distinctly crystalline. The junction was 



* Contacts could certainly be found by further searclung. The bluffs at Shady 

 Side Landing, a few miles down the river, and under Englewood Hotel, two miles up 

 stream, scorned worth visiting, as seen from a passing boat. Mather (282) gives 

 examples of contacts farther north ; some of his figures are here copied (figs. 11-14). 



t *0ook mentions sandstones overlying the trap at Englewood (&, 178, 208). I was 

 directed to Mill Brook, as a stream likely to show the desired contact, by Mr. J. II. 

 Scrviss, of Englewood, 



A small stream known as Mill Brook, shown close to 



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