PETROLOGICAL ABSTRACTS AND REVIEWS 
BERKEY, CHARLES P. Geology of the New York City Aqueduct. 
N.Y. State Museum, Bull. 146, 1911. Pp. 283, figs. 39, pl. 38. 
“Studies in Applied Geology” is the alternative title of this rather 
unusual work; a caption happier, and far more suggestive than that 
appearing on the cover of the book, for the value of the data gathered 
concerning the geology of this region, while great as a matter of record, 
is still entirely subordinate to the interest accruing from the statement 
of the methods used by the author in the solution of the numerous 
problems propounded to him as the consulting geologist of the New York 
Board of Water Supply. Probably in no previous engineering enter- 
prise has such weight been placed upon the testimony of the geologist, 
and certainly in few has he been called upon to accumulate facts sufficient 
to enable him to forecast geological conditions with great accuracy over 
such a large area. 
The author has wisely refrained from making his report a mere cata- 
logue of the facts ascertained. ‘“‘It is one of the most cherished wishes 
of the writer of this bulletin that some of the problems may be presented 
in such a manner as to serve a distinct educational purpose.” To this 
end the problems are developed in the text nearly as they arose in the 
field—the data are given, with the particular information sought by the 
engineers; then follows the line of reasoning, and the conclusions 
reached; and finally the actual state of affairs, as shown by further 
exploration, is recorded. 
The aqueduct, now in course of construction, is designed to carry 
over half a billion gallons daily, from the Ashokan Reservoir in the 
Catskill Mountains, to the Hill View Reservoir, just outside of the city, 
and includes 92.5 miles of aqueduct, with ro dams; and 18 miles of 
additional tunnel, with 16 miles more of delivery pipe line in New York 
City itself. 
From the Catskills south to the Highlands the territory under con- 
sideration is underlain by Paleozoic sediments, practically complete in 
section from Lower Cambrian to Upper Devonian, nearly flat and of 
simple structure to the north, but becoming more complicated in the 
Hudson River slate region farther down the river. The district lying 
to the south is underlain by ancient and very complicated crystalline 
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