20 The American Geologist. July, 1894 
basins of the unevenly laid later drift which are so strongly 
contrasted with the smooth and attenuated outer portion of 
the drift sheet beyond the moraines. 
THE PRESENT CONDITION OF THE EARTH'S IN- 
TERIOR AS VIEWED FROM THE STANDPOINT 
OF THE NEBULAR HYPOTHESIS. 
By Prof. W. H. Beamoh, Rolla. Mo. 
Although there are now but few, if any, geologists who 
would contend that the earth consists of a cold crust sur- 
rounding a melted interior. many of them, particularly writ- 
ers of text-books, still teach that the earth's interior is very 
highly heated. While we do not find in any recent literature 
any positive statement as to the degree of heat, I am sure 
that I make no mistake, when I assert that Dana, Le Conte 
and Geikie, all give the impression, perhaps unintentionally, 
that the temperature of the earth's interior is so great that, 
were it not for the weight of the superincumbent crust, all 
of it would be in a molten condition, at a temperature much 
hotter than necessary for complete fusion. 
Dana says : "The rate 1° F., for 60 feet of descent, in 
the latitude of New York, would give heat enough to boil 
water at a depth of about 9,000 feet : and 3,000° F., at a depth 
of about 33 miles. But the ratio is not an arithmetical one,, 
because both of the greater conductivity of the earth below 
(owing to greater densit}*) and the increased pressure, and 
hence the depth of fusion, supposing fusion a fact, much ex- 
ceeds this amount: but how much, has not yet been deter- 
mined."* 
Le Conte says : "From the facts given above it is probable 
that the temperature of the interior of the earth is very great.' f 
After a very clear and able argument showing the effects of 
pressure in deepening the fusion level, if fusion exists at all, 
he sa3 T s : "From this line of reasoning, therefore we conclude 
that the solid crust of the earth must be much thicker than 
is usually supposed, and there may be even no interior liquid 
at all." + 
r 
-Dana's Manual of Geology, page 717. 
•f-Le Conte's Elements of Geology, third ed. (1891 1, pag€ 84. 
JLe Conte's Elements of Geology, page 86. 
