On the Physical Geology of the United States, §c. 13 
characters over vast areas, the general similarity of organic con- 
tents not only on the American continent but even in Europe, 
indicate that the causes of these depositions and the conditions 
under which they were deposited from the ocean, acted with 
great uniformity over extensive portions of the earth’s surface. 
The polar and equatorial currents are believed to be adequate for 
the production of the effects observed. Without farther expla- 
nation, the foregoing conclusion might be deemed unsupported 
by other evidence than probability. 
In the final Report on the geology of the first district of New 
York, I have adduced the facts that first led to the observation 
of the directions of currents during the deposition of the sedimen- 
tary rocks. These facts when grouped, led from one generaliza- 
tion to another, until it was found that the cause was not con- 
fined to the United States or Europe, or even to the northern 
hemisphere, but in like manner affected the southern. The 
cause then was one affecting the earth. ‘The great and perma- 
nent currents of the ocean, modified in direction and velocity by 
known physical laws, by the trend of coasts, and the contour of 
the former bed of the sea, were found to harmonize with the 
phenomena of depositions in the United States. 
In the geological report above referred to, I have shown, (1st,) 
by means of the direction and distance of transport, that the 
distribution of bowlders and drift is such as would necessarily 
be the result, if such currents existed; and that the probabilities 
are that no other cause could have distributed them in a manner 
so peculiar.* 
2. That the quaternary, composed of sands, clays, and loam, 
so extensive and uniform in composition and aspect, must have 
been owing to a cause as general as this.+ 
3. That the sand and gravel beds of the quaternary, so exten- 
sive in some parts of New York, are situated where conflicting 
currents must necessarily have met and formed eddies, if the 
country was beneath the level of the ocean.} 
A, That the distribution of organic life, (being extremely 
abundant in some parts, and as rare in the same continuous rocks 
* Natural History of New York, Part1V, Geology of Ist District, by W. W. 
Mather, pp. 197, 210-213, 217, 218, 222-228. 
t Idem, pp. 129, 148-156. 
¢ Idem, p. 148-150, 
