A, Lindenkohl—Geology of the Sea-bottom, ete. 475 
Art. LXII.— Geology of the Sea-bottom in the approaches to New 
York Bay; by A. Linpenkou., U. S. Coast and Geodetic 
Survey. With a plate (Plate IV, unnumbered). 
[Read at the meeting of the National Academy of Sciences, April 22, 1885, by 
J. E. Hirearp.] 
DuRING the survey of the sea-approaches to New York in 
the years 1842 and 1844, specimens of sea-bottom were col- 
lected while soundings were in progress. The samples were 
examined under the direction of Professor Bache by Assistant 
L. F. Pourtales of the Coast Survey Office and by Professor J. 
'W. Bailey of West Point, N. Y., and the results of analyses 
were published as Appendix No. XI with the Coast Survey 
Report for the year 1869. The investigations by these natu- 
ralists attracted attention and ended in opening the way toa 
field of scientific inquiry which, at this time, is cultivated by 
men eminent in such researches in all the leading nations. 
Neither. of the naturalists here named is now living. 
Within the last five years, minute hydrographic surveys 
have been made of the same locality. Some collateral informa- 
tion also has been furnished by the Geological Survey of New 
Jersey under the direction of Professor George H. Cook. We ° 
are thus enabled to invest deductions with increased precision, 
and to extend inquiry beyond the limits to which Assistant 
Pourtales restricted himself. 
The sea-bottom off the entrance to New York lower bay is 
characterized by features peculiar to that region. These in- 
clude : 
ude: 
1. A well defined submarine valley. 
2. An area of clay bottom extending about one hundred 
miles seaward. 
3. A deep ravine at the edge of the continental cine 
The features here specified will be separately described. 
Submarine Valley.—The early survey of the neh pcre 
to New York developed the existence of a series of “ deep 
mud holes” lying in a straight line off the entrance. These 
it was supposed might serve as guides to mariners, but no: 
special significance was attached to the “mud holes” t 
Professor Dana, from a study of the Coast Survey soundings, 
showed that they lay in the course of a valley-like depression 
which had the right position to have been, in a period of higher 
evel, the continuation of the Hudson River channel. When 
these views were communicated to the Coast Survey Office 
these mud holes were at once recognized as indications of such 
a channel, and it was surmised that they actually form a con- 
tinuous channel instead of being separated. The last survey 
