NEW JERSEY. 465 



The serpentine, which forms so conspicuous a feature in the geology 

 of Staten Island, is thought by Mr. liritton to be a metamorphosed 

 magnesiau hmestone. The sections drawn to illustrate 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 

 are 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^f 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 JERSEY. 



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

 Prof. H. D. Rogers, 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 lodes or veins." 

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

 under that of Professor Cook, agi-ee in making the' crystalline lime- 

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

 Professor Cook states (Geology of New Jersey, 18(18, p. 4-4) that the 

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

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

 rock." 



By Professor Cook the whole system of rocks, including the gneiss 

 and crystalline limestones, together with the associated iron and zinc 

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

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



VOL. VII. NO. 11. 30 



