The Bamboo Iron Ore. — U'inchell. 253 
horizon of the ig;noous rocks of the Manilou epoch. It is pos- 
sible that the next lower iron ore is similarly related to the 
Cabotian, the oldest igneous rocks of the Keweenawan. It 
would be no abnormal fact that the highly ferruginous shales 
of the Keweenawan should be found to afford in some places 
so concentrated a condition of their contained hematite as to 
become economically a valuable iron. 
THE CRETACEOUS EXPOSURE NEAR 
CLIFFWOOD, N. J. 
By IiDWAKi) W. P.KKKV, I'assaic, N. J. 
I'LATE XV. 
In the January number of the American Geologist there 
appeared an article criticising certain views ascribed to the 
writer as to the proper correlation of the Cretaceous clays 
which outcrop on Raritan bay in the vicinity of Cliflfwood, X. 
J. The Article in question is written in a tone that should not 
be permitted in a scientific discussion, particularly as the pa- 
per criticised was intended as a contribution to paleobotany, 
the geological discussion being merely introductory and ad- 
vancing no new ideas or correlations ; on the contran*' it con- 
tained simply a brief resume of the opinions of the several ge- 
ologists who had studied this exposure and whose mature 
opinions had been before the public for a number of years. 
Should subsequent facts warrant, which, it seems to me they 
fall far short of doing at present, the reference of these 
clavs to the Raritan formation I would most readily accept 
this conclusion, although the evidence of the contained flora, 
largelv misunderstood and misquoted by Knapp. does not 
warrant such a conclusion. 
Professor \\m. B. Clark who named the formation and 
mapped it for the United States Geological Survey, and whose 
views I followed in a general way in my article above referred 
to writes me in part as follows in response to a letter asking 
for his opinion : 
"There is no question as to tlic sharpness of the Matawan-Raritan 
contact from the Potomac valley northward. It is one of the most 
marked stratigraphic features in the Maryland-New Jersey Cretaceous 
belt. As we approach the Raritan river at Cliflfwood blufif coming 
