INTRODUCTION. 
95 
NOTE E. 
I have already alluded to the explanation, given by Sir John Herschel, of the 
process by which continental areas may be elevated from the accumulation of de¬ 
posits upon the ocean bed. I have seen this explanation only as published in the 
appendix to Babbage’s Ninth Bridgwater Treatise, as an extract of a letter from 
this philosopher to Sir Charles Lyell. Since this and another letter to Lyell, and 
one to Sir R. I. Murchison, contain many suggestions which seem to me as offering 
support to the views I have advanced, I have made some extracts which follow : 
After discussing the question of the rise of the isothermal surfaces beneath the 
earth’s crust from the deposition of new matter on the bed of the ocean, a view 
which appears to have originated in the minds of Babbage and Herschel quite 
independently of any knowledge of each other’s conclusions, he goes on to speak 
as follows (alluding to Lyell’s Principles of Geology) : 
“ According to the general tenor of your book, we may conclude that the greatest transfer 
of material to the bottom of the ocean is produced at the coast line by the action of the sea, 
and that the quantity carried down by rivers from the surface of continents is comparatively 
trifling. While, therefore, the greatest local accumulation of pressure is in the central area 
of deep seas, the greatest local relief takes place along the abraded coast lines. Here, then, 
in this view, should occur the chief volcanic vents. If the view I have taken of the motion¬ 
less state of the interior of the earth be correct, there appears no reason why any such influx 
of heat should take place under an existing continent (say Scandinavia) as to heat incum¬ 
bent rocks (whose bases retain their level) 5 or 600° Fahrenheit for many miles in thickness 
( Princ. of Geology, Yol. ii, p. 384 : 4th edition). Laplace’s idea of the elevation of sur¬ 
faces due to columnar expansion (which you attribute, in a note, to Babbage), is, in this 
view, inadequate to explain the rise of Scandinavia or of the Andes, &c. But, in the varia¬ 
tion of local pressure due to the transfer of matter by the sea, on the bed of an ocean im¬ 
perfectly and unequally supported, it seems to me an adequate cause may be found. Let A 
be Scandinavia, B the adjacent ocean 
(the North Sea), C a vast deposite newly 
laid on the original bed of the ocean, 
E E E a semifluid or mixed mass on 
which D D D reposes. What will be the 
effect of the enormous weight thus added 
to the bed DDD( rock being heavier 
than sea) ? Of course, to depress D 
under it, and to force it down into the 
yielding mass E, a portion of which will be driven laterally under the continent A and up¬ 
heave it. Lay a weight on a surface of soft clay : you depress it below, and raise it around 
the weight. If the surface of the clay be dry and hard, it will crack in the change of figure.” 
