314 
THE GEOLOGIST. 
Lallij/ni.f Aphdca and Latlit/ms NissoVta have been very abundant this year 
on the Kciiper sandstones and marls, bnt Mr. Symouds has not seen a single 
specimen of the former plant u])on the adjoiiiiug Lias of the district. Carex 
moiitana grows only on earboniferons limestone. The rarer plants of Snowdou 
appear to have selected bands of volcanic tuff, intermingled with calcareous 
deposits for their habitat. Mr. Symonds jiarticularly asked for the attention 
of geologists to the lUora of insulated trap rocks. 
ON THE CORRUGATION OF STRATA IN THE VICINITY OF 
MOUNTAIN RANGES. 
By the Rev. J. Dingle. 
This paper was in continuation of some former papers which had been read 
before the Association, in which an attempt had been made to determine the 
mode of the formation and development of the earth's crust, from physical, 
geographical, and geological considerations. The author described the varying 
forms of flexure, diminishing in intensity with their distance from the igneous 
axis, which characterizes the strata in the neighbourhood of the mountain 
chains, and showed how this form would arise from the action of the molten 
interior of the earth near the fissures in the crust. The fluid lava rising in a 
fissure must have reacted on the general mass Ijeneath, and caused an upward 
pressure on the crust on each side. Now it has been proved by experiment in 
the ease of a column of fluid, that, in the propagation of the condensation 
produced by the weight of the column, there were points of maximum and 
minimum pressure along the surface of the fluid from which the cohimn arose ; 
and hence in the ease of the fissures we might generally expect successive cor- 
rugations, subsequently lifted up, and sometimes falling over at last into one 
dip, just as we actually find them. The author expressed his obligations to 
Professor H. D. Rogers for the valuable information which he had derived 
from an important paper of his on the subject in the Transactions of the Royal 
Society of Edinburgh for 1857, but demurred to some of his hypotheses. 
Flexures at definite ])oints in solid strata must be produced by repeated and 
continued fissures, and not by paroxysmal action. The latter chiefly spends 
itself in earthquakes and volcanos, which, upon the whole, can produce no con- 
tinuous change of form. The two kinds of forces appear, however, to be inti- 
mately related to each other ; and if we suppose the one to be only tlie other 
in excess, we are supplied with a simple explanation of the connection between 
the corrugated mountain chains, and the lines of earthquakes and volcanos. 
As a corollary from the above views, it might be observed that they destroyed 
the idea of any distinct theory of volcanos, whether of elevation or eruption; 
for the quantities of elevated and ejected matter in the case of a fissure or a 
ruptured corrugation might be in all possible proportions to each other. 
The author expressed his confidence that in this and his former papers he had 
pointed out the true means of determining the mode of formation of the 
earth's crust from the consideration of existing facts and well-knowTi physical 
laws — a branch of geological science in which nothing had been done before 
beyond starting a few crude and ill-supported guesses. 
A brief conversation followed the reading of the paper, in which Professor 
Rogers expressed his general acquiescence with the author's views on some 
important points connected with the formation of the earth's crust. 
