( 84 ) 
below the old Cretaceous peneplain. The earlier valley of 
the Bronx doubtless represents its Tertiary erosion in the 
Cretaceous peneplain of Westchester County, while the gorge 
is of Glacial and Post-glacial development. 
The portion of the geological history of the Bronx, there- 
fore, that is discussed in this paper is so recent that it has 
not been felt to be necessary or appropriate to review the 
general production of the Cretaceous peneplain, whose stumps 
now form our singularly even hilltops and horizon line, but 
in the paper cited below its development will be found fully 
set forth.* The recent geologic history of the neighboring 
coast has a more direct bearing. As regards Long Island 
Sound, Professor Danat has supplied some very important 
points in the record. It is altogether probable that Long 
Island Sound was a river valley during a part at least of the 
Glacial Period, certainly before the ice covered it and built 
up the Long Island moraines. A well marked channel is 
still shown by soundings along the north shore of Long 
Island, and it is necessary to assume an elevation of 100 feet 
above its present position in order to account for these condi- 
tions. Other channels are also indicated, now, of course, 
drowned out by the Sound and choked up as regards some of 
their old outlets by drift. 
few months after the publication of Professor Dana’s 
paper, Dr. F. J. H. Merrill} recorded and interpreted evi- 
dence that indicates for the neighboring Hudson Valley ups 
and downs that of course the Bronx must have shared. Dr. 
Merrill states that, after the retreat of the continental glacier 
from this section, the land stood for a long time at a minimum 
depression of 80 feet below its present level. A gradual ele- 
*W. M. Davis, The Geological Dates of Origin of certain Topographic 
Forms on the Atlantic ee of the United States, Bulletin Geological So- 
ciety of America, II., 545, 
tJ. D. Dana, Long ee Sound in the Quaternary Era, with Observa- 
tions on the Submarine Hudson River Channel, Amer. Jour. Scz., Decem- 
ber, 1890, p. 425. See also John Bryson, Amer. Geol., November, 1896, p. 
32 ee 
F. J. H. Merrill, Post- SS History of the Hudson River Valley, 
a Jour. Scz., Jane, 1891, p. 460. 
