Dikes of the Hudson River Highlands. 691 
called ‘Wingless Birds,’ Fossil and Recent, and a Few Words on 
Birds as a Class,” in Proc. Geol. Ass., Vol. IX., February, 1886, 
No. 5, p. 352, pls. I—II., London Univ. College, 1887. 
L. Woolman has “Geological Results of the Boring of an Arte- 
sian Well at Atlantic City, N. J.,” in Proc. Acad. Nat. Sci. Phila., 
Part III., p. 339. 
J. L. Wortman has an article “On the Teeth of the Vertebrata” 
in AMER. NATURALIST, Vol. XXI., p. 463. 
J. Young has “Note on a New Family of the Polyzoa—Cysto- 
dictyonidæ (E. O. Ulrich)—with Notice of Three Carboniferous 
Species,” in Trans. Edinburgh Geol. Soc., Vol. V., Part III., 
. 461. 
THE DIKES OF THE HUDSON RIVER HIGHLANDS. 
BY J. F. KEMP. 
ŢEE cuts of the West Shore Railway, on the Hudson river, above 
Haverstraw, and below Cornwall, have done much service to 
geology in bringing to light the subsurface and unaltered structure 
of the Archæan rocks. The Stony Point cut did more than any 
other exposure to convince Professor J. D. Dana of the intrusive 
character of the now famous Cortlandt series.! It exhibits as well 
one of the most interesting examples of the contortion of mica 
schists on the contact with intrusive rocks which any known area 
affords. Here also Dr. Geo. H. Williams found the types of his 
hornblende-peridotite? and was especially aided in his careful 
studies of the series. Beyond Stony Point the railway crosses the 
belt of blue limestome so extensively quarried at Tomkins’ Cove, 
and then in the foot of the Dunderberg meets the main mass of the 
Highland Archean. Through this it has made its way by cuts, 
excavations and tunneling a distance of seventeen miles to Cornwall, 
where it again passes off the Archean. 
Am. Jour. Sci., III Series, vol. xxviii., p. 384. 
Ibid., vol. xxxi., p. 29. 
9 . . 
