Dr. CO. Ricketts—Oscillation of the Earth's Crust. 303 
of subsidence and accumulation are dependent the one upon the 
other, that Captain C. E. Dutton of the United States Ordnance 
Survey considers that “few geologists question that great masses of 
sedimentary matter displace the earth beneath them and subside.” * 
This statement by Dutton cannot refer to geologists on this side of 
the Atlantic, by whom, it may be said, the subject has hardly been 
taken into consideration. 
Sir John Herschel, in a letter to (Sir) Charles Lyell, dated 1836, 
made slight allusions to the effect which “the transfer of pressure 
from one part of the earth’s surface to another would have on the 
fluid or semi-fluid matter beneath the outer crust.” He supposed 
that “if the whole floated on a sea of lava, there would merely be an 
almost infinitely minute flexure of the strata.”* He subsequently 
(in 1859) showed that “the bed of an ocean supported on a yielding 
substratum may be depressed, without a corresponding depression of 
its surface, by the simple laying on of material;”* and in a popular 
lecture illustrated the consequences resulting from the increase of 
pressure in one place and relief in others by what would occur to a 
ship floating even on her keel. “If the weight on the starboard be 
transferred to the port side, she will heel over to port; so if the 
continents be lightened, they will rise; if the bed of the sea receives 
additional weight, it will sink.”* The theory did not receive such 
attention as was due to the great authority from whom it emanated ; 
perhaps because the illustrations advanced did not afford sufficient or 
conclusive proof. 
In the Geological Record for 1877 (p. 178) a French geologist is 
stated to regard the increasing weight of deposits in areas of subsi- 
dence as the chief factor of geological change.® | 
Besides these authors, no one having authority such as would 
influence geological opinion has, until within the last few months, 
considered the subject, though the records of the simultaneous occur- 
rence of accumulation and subsidence are almost innumerable. Those 
who have watched the progress of geology must with Darwin “have 
been surprised to note how author after author, in treating of this or 
that great formation, has come to the conclusion that it was accumu- 
lated during subsidence ;”® and it appears to me equally as great 
a wonder that so little endeavour has been made by these authors to 
determine whether the two classes of phenomena should be associated 
as cause and effect. 
Mr. J. Starkie Gardner, F.G.S., in the Grotocican Magazine for 
June, 1881,’ and the Rev. Osmond Fisher, F.G.S., in his book 
1 The Geological History of the Colorado River and Plateaus, Nature, vol. xix. 
1879, p. 251. 
g Pe rccedines of the Geological Society, vol. 11. p. 548. 
3 Physical Geography, by Sir John F. W. Herschel, Bart., F.R.S., etc., § 182. 
4 About Volcanos and Earthquakes, Familiar Lectures, Lecture I. p. 11. 
5 V. H. Hermite, Sur Vunité des forces en Géologie, Compt. Rend. t. \xxxiv. 
pp. 459-461, 510-512. 
6 Onthe Origin of Species, by Charles Darwin, F.R.S., chap. ix., third edition, p. 313. 
7 Subsidence and Elevation, and on the Permanence of Continents, Gnou. Mac. 
Deg Ei Vol ME ps 241. 
