28 NEW YORK STATE MUSEUM 
mitic marbles. North of the Highlands there is a great thickness of slates, 
good raw materials from which to produce mica-schists by metamorphism. 
The slates rest upon a heavy stratum of blue magnesian limestone, the Wap- 
pinger, well adapted to yield dolomitic marbles under metamorphism. 
Only a poor representative of the Poughquag quartzite could be found 
beneath the marbles on the south side, but a quartzitic rock was noted by 
Doctor Merrill and called the Lowerre, from a suburb of New York City. 
This interpretation for which there was indeed much reason, was. generally 
accepted for the Manhattan schist and the Inwood limestone and was used 
in the New York City folio (Folio 83) of the U. S. Geological Survey. The 
crucial point arises, however, when we endeavor to trace the belts along 
the valleys from the south respectively into the Wappinger limestone and 
Hudson River slates on the north. In applying this test C. P. Berkey 
found himself not only unable to make out the transition but confronted 
with undoubted faulted relations of the Paleozoic with Manhattan schist 
and the Inwood marble on the south. An equivalent of the two sets seemed 
so improbable that a different view was advanced. The schist and marble 
were referred to a Precambrian group of sediments, which, however, were of 
late Precambrian age. This view is further corroborated by the fact that 
the Poughquag quartzite displays 600 feet of section on the north side of 
the Highlands whereas 20 miles to the south there is no satisfactory equiva- 
lent. It is also true that the Manhattan schist is a much more extreme 
case of metamorphism than is any representative of the Hudson River slates 
in Massachusetts or Vermont. (p. 705-6) 
Berkey’s interpretation, which is undoubtedly correct, is so 
diametrically opposed to the older views that the writer has felt 
constrained to quote at length from Professor Kemp’s paper. 
The Precambrian sediments in the contiguous territory of New 
Jersey were studied by Bayley,” who showed that the Franklin 
limestone is only one member of a series of Precambrian sediments 
which consists, in addition to the limestone, of quartzites, con- 
glomerates, slates and micaceous and graphitic schists, some of which 
are so thoroughly metamorphosed that their original clastic character 
is greatly obscured. 
The recognition of this series, which may tentatively be referred 
to the Grenville, and the realization that these rocks were highly 
metamorphosed, folded and strongly foliated before the invasion of 
the igneous masses called Pochuck, Losee and Byram gneisses by 
the New Jersey geologists, and the Storm King granite, Cat Hill 
granite, Canada Hill granite, Reservoir granite and Mahopac granite 
by Berkey “ was an important step toward the final untangling of the 
complexities of Highlands geology. 
71 Bayley, W. S. The Precambrian Sedimentary Rocks in the Highlands 
of New Jersey. Congres Géologué Internationale Comptes Rendus 12, 1913, 
p. 325-34. Ottawa, I914. 
72 Berkey, 'C. P. Geology of the New York City Aqueduct, N. Y. State 
Mus. Bul. 146. ro11. Also Berkey, C. P., & Rice, Marion, Geology of the 
West Point Quadrangle; State Mus. Bul. 225-226. Berkey earlier (10907) 
recognized the old series of Precambrian sediments in the Highlands of south- 
eastern New York. See N. Y. State Mus. Bul. 107, Structural and Strati- 
graphic Features of the Basal Gneisses of the Highlands. 
