640 Granite at Mounts Adam and Eve. 



Briefly, is the white crystalline limestone Archeean in age, deposited 

 on the gneisses and granites, and regionally metamorphosed, while 

 the blue is a later overlying Cambrian deposit ; or, are they both 

 one and the same formation, originally blue, of which the part next 

 the great, intruded granite knobs and dikes, now perhaps gneissic, 

 has been metamorphosed by this intrusion to white, and charged 

 with silicates? Keating and Yanuxem (1822),^ C. U. Shepard 

 (1832), 2 Cook (1868),^ and Britton (1886),* have supported the 

 former; while Nutall (1822),^ Rogers (1836),^ Mather (1843),' 

 Nason (1890)^ have urged the latter. Kitchell, State geologist of 

 New Jersey from 1854-1861, did not definitely commit himself, 

 and the results of the U. S. Geol. Survey, under J. E. Wolff, are 

 not yet available.^ There is still a third view possible, to wit, that 

 the white limestone is Archaean in age, but metamorphosed along 

 granite intrusions, and so charged with minerals, while the blue is 

 later. These contact effects we regard as beyond question, how- 

 ever uncertain the relations of the blue and white limestone may 

 be regarded. 



Difficulties in Reaching a Decision. — There are difficulties in the 

 way of deciding the stratigraphic relations of the two which become 

 apparent in the field. In Orange County the region is richly culti- 

 vated, and outcrops are not as numerous as one could wish. Even 

 when they are to be seen, the white limestone is almost entirely 

 lacking in dip and strike, and is of very massive character. At no 

 point were we able to trace either variety to an actual contact with 

 the other; but we did find the outcrops along the road running due 



1 Jourp. Phila. Acad. Sci., 1822, p. 277. 



2 Amer. Joiirn. Sci., i, xxi, p. 323. A geological map of the vicinity of Mt. 

 Adam and Mt. Eve, by Messrs. Young and Heron, accompanies this paper, and 

 is reprinted in Mather's Rept. (see Reference 7) as Plate 41. 



3 Geology of New Jersey, 1868, p. 310. The same view is upheld in later 

 reports, notably on the geological map accompanying that of 1880. 



* New Jersey Survey, 1886, pp. 77-83. 



* Amer. Journ. Sci., i, v, p. 247, last paragraph. 



6 Geological Survey of New Jersey, Report of 1840, pp. 47-67 (as quoted by 

 Nason). 



' Report on the Geology of the Fourth District, N. Y., p. 465, fifth para- 

 graph . 



8 Annual Report N. J. State Survey, 1890, pp. 25-50. 



* Reference should be made to the recent paper by A. F. Foerste (Amer. 

 Journ. Sci., Dec. 1893, p. 435), who discusses fossiliferous localities in the blue 

 limestone, etc. 



