Distribution of the Loess. — IVright. 215 
or five feet, to be very liberal, for the United States and British 
America. Supposing the area of the latter to equal the former, 
there would then be 250 cubic miles of water a year or ten times 
the amount now discharged by the Missouri river. In this no 
account is taken of the water drained from the rest of the basin 
which was certainly no less than now. If counting the exten- 
sion into Canada by the Saskatchewan as equal to the area oc- 
cupied by the ice it may be put down as a moderate calculation 
that the river discharged eleven times as much water as at the 
present time, with the probability that it discharged at least 
for certain years twenty times as much.'"'' 
Professor J. D. Danat had made similar calculations con- 
cerning the supply of water from the melting ice in' the valley 
of the Connecticut river as I had also done at an earlier date 
concerning that in the upper portion of the Delaware valley. $ 
Professor Dana calls attention to the aid which would be given 
in melting the ice in the last stages of the Glacial period 
through the existence of crevasses of great extent and of sur- 
face and subglacial streams of water, producing open chan- 
nels and tunnels, which would greatly add to the exposed sur- 
faces. He also supposes that the presence of the ice would 
greatly increase the precipitation, so that the supply of water 
would be greatly enlarged from that source as well as from 
the melting of the ice. Altogether he thinks it not improbable 
that 460 cubic miles of water were for a short period annually 
set free by the melting of the ice over an area of only about 
8,000 square miles.* 
Professor St. John has favored me with more detailed cal- 
culations, as follows : — 
"The quantity of heat received during a year by the region 
of the earth lying between latitudes 41° and 50° N. may be 
found approximately. Assuming the solar constant to be 30 
calories ])cr square meter, the heat from the sun falling verti- 
cally upon an equatorical section of the earth would be suffi- 
cient to melt a layer of ice about 700 feet thick in a year. The 
quantity of heat per unit area varies with the sine of the sun's 
•"The Formation of the Quaternary Deposits In Missouri, Mo. Geol. Sur.. 
vol. X, pp. 114-217, 1896. 
fThe Flood of the Connecticut Valley from the Meltlnp of the Quater- 
nary Glacier." Am. Jour. Sci., vol. xxlli, pp. 87-97. 179-202. 360-373, 1882. 
t"An Attempt to Estimate the Age of the Palseollthlc-bearlng Gravels in 
Trenton, N. J.," Proc. Boston Sac. Nat. Hist., vol. xxi, pp. 137-145, 1881. 
