370 J. p. KEMP — GRANITES OF ATLANTIC COAST 



ished columns or hammered blocks the granite exhibits a fluidal arrange- 

 ment of tlie components that is strongly suggestive of the flow jDhenomena 

 in i)or])h3a-itic rocks, and yet it is most probably the result of plasticity 

 induced b}'' pressure. The strength of this conclusion is increased by the 

 pronounced gneissoid phase of this rock that is the basis of the large 

 quarry industry on Hoadlys point just south of the Leets Island station 

 and a mile or two east of Stony creek. This coarse, red gneiss is certainly 

 a phase of the Stony Creek red, and it assuredly owes its foliated character 

 to dynamic metamorphism. Under the microscope the quartzes are 

 crushed and strained, the orthoclases have undulatory extinction, mi- 

 crocline is abundant, and the biotite is dragged out into streaks whose 

 origin is very apparent. These results of squeezing are much more 

 pronounced at Hoadlys point than at Stony creek and the easing of the 

 pressure must have been especially accomplished at the former locality. 



The Stony Creek red shows some pronounced pegmatitic developments 

 in the midst of the normal grain, but the constituent minerals do not 

 appear to vary much, except in the introduction of pyrite, which may 

 be quite noticeable. 



The Stony Creek gray variety is more finely crystalline than the pre- 

 ceding and contains more plagioclase, which being of a wdiite color makes 

 the general effect of the rock lighter. The analyses, as later shown, are 

 also somewhat contrasted. The component minerals are quartz, ortho- 

 clase, microcline, oligoclase, a little biotite, magnetite, apatite, zircons, 

 and large garnets, 10 millimeters in diameter, which produce red spots 

 throughout the general mass of the stone. In thin-section the garnets 

 show no regular outlines, but are irregularly ramifying anhedra. Effects 

 of strain are frequent in the rock and it has evidently suffered from 

 djniamic metamorphism. 



INTRUSIVE NATURE OF THE GRANITES 



The contacts. — In all cases where the contacts of the granites and the 

 gneisses are visible they are, in the opinion of the writer, plainly irrup- 

 tive. Although the mineralogy of the two rocks is so nearly the same, it 

 is possible to distinguish clearly between the massive and the foliated 

 individuals. Nearly all of the quarries show these phenomena, but the}'' 

 are especially well exhibited in the quarries south of the railway, at 

 Westerly, at Millstone point, and in the Brooklyn quarry at Stony creek. 

 The granites tongue out irregularly into the gneiss, -precisely as if the}' 

 had been intruded into a shattered country rock, which, however, must 

 have been itself sufficiently hot to have had no percei^tible chilling 

 effect on the intrusion. Fragments of gneiss are found in the granite, 

 especially at Millstone point. These mixtures of gneiss and granite and 



