NEW JERSEY. 



4G5 



The serpentine, which forms so conspicuous a feature hi the geoh)gy 

 of Statcn Island, is thought by Mr. Britton to be a metamorphosed 

 magnesiau hmestone. The sections drawn to ilhistrato the geology of 

 the region show the serpentine always occurring as a sort of mantle 

 enveloping the gneiss. These sections, which seem to be a pure fiction 

 of the imagination so far as the relations of the serpentine and gneiss 

 aro concerned, do not agree with the geology as laid down on the 

 accompanying map. Since, as is well known, a large part of the thor- 

 oughly-studied serpentines of the world have been proved to be the 

 result of the metamorphism of eruptive masses, it seems more reason- 

 able to ascribe such an origin to the rock in the region under considera- 

 tion. At all events, the sections given do not favor the idea of such an 

 origin of the serpentine as is advocated by Mr. Britton ; nor is it by any 

 means proven that the belt of metamorphic rocks which runs through 

 Staten Island is, as he supposes, older than Lower Silurian. 



NEW JEBSEY. 



In the Report of the earliest Geological Survey of New Jersey, by 

 Prof. 11. D. llogers, the gneissic belt which traverses that State from 

 northeast to southwest in its northern portion is called primitive, and 

 the crystalline limestones which accompany it are supposed to be the 

 result of an alteration of the Blue Limestone by the agency of dikes of 

 granite. The beds or masses of iron and zinc ore, which characterize 

 the gneissic belt, are said to be '' unequivocally genuine lod(^s or veins." 

 The later Survey, first under tlie direction of Dr. Kitchell, and later 

 under that of Professor Cook, agree in making the crystalline lime- 

 stones a portion of the gneissic formation. In regard to the iron ores, 

 IVofessor Cook states (Ceology of New Jersey, 1808, p. 41) that tlie 

 majority of geologists now think them to be true beds, "which were 



deposited as sediments, in the same way as the material for tlie gneiss 

 rock.*' 



By I'rofessor Cook the whole system of rocks, includintr tlie oticIss 

 and crystalline limestones, together with the associated iron and zinc 

 deposits, are considered as belonghig to the "Azoic formation." These 

 rocks are overlain, as represented in the published sections, by the 



VOL. VII. — NO. 11. 30 



