CURRENT PRE-CAMBRIAN LITERATURE 703 
places in Dutchess county, are overlain unconformably by quartzites, 
which are believed to be of Cambrian age. 
Ries* describes the geology of Orange county, New York. Pre- 
Cambrian rocks form the Highland region in the eastern part of the 
county, the northwestern side of Bellvale Mountain, and a series of 
rounded knob-like hills extending from Sugar Loaf village to Newburgh. 
They comprise gneiss, at times massive and resembling granite and 
limestone. The crystalline rocks are folded and faulted, the folds 
plunging frequently to the northeast. 
In the south-central part of the county is found an area of white and 
blue limestone, which continues south into New Jersey. ‘The white 
limestone is found in New Jersey to contain fossils of Cambrian age. 
Exposures are found east of the road, 114 miles west-southwest of Pine 
Island station, which show the passage of the blue into the white lime- 
stone. Other, similar areas of limestone are found to the northeast. 
Limestones interbedded with the gneisses are found at Popolopen 
Pond, and again at Fort Montgomery. 
Wolff and Brooks’ present a final discussion of the age of the 
Franklin white limestone, of Sussex County, N. J. The pre-Cambrian 
age of the white limestone is believed to be shown by the following facts : 
The supposed cases of interbedding of the white limestone and the 
Cambrian quartzite are found to be due to faulting, or to peculiar con- 
ditions of deposition. On the other hand, while it is difficult to prove 
that the white limestone and pre-Cambrian gneiss are actually inter- 
bedded, narrow bands of the true gneiss do occur within the white 
limestone belt, and seem to be an integral part of the series. 
The granite occurring in the area isintrusive in the white limestone, 
and the nature of the contacts of the granite and the Cambrian quartz- 
ite indicates that the intrusion was prior to the deposition of the Cam- 
brian quartzite and blue limestone. While the intrusion of the granite 
has caused local metamorphism of the white limestone, it is believed 
that the crystallization of the limestone antedated the granitic intru- 
sion, and was contemporaneous with the crystallization of the gneisses 
in their present form. 
* Geology of Orange county, by HEINRICH RIEs: Forty-ninth Ann. Rept. of N. Y. 
State Museum, for 1895, Vol. II, 1898, pp. 395-475. With geological map. 
2 The age of the Franklin White limestone of Sussex County, N. J., by J. E. WOLFF 
and A. H. Brooks: Eighteenth Ann. Rept. U.S. Geol. Surv., Part II, 1898, pp. 425—- 
457. With geological map. 
