Chap. XX.] 
INTENSITY OF FORMER CAUSES. 
489 
tion and renovation of the surface, there were formerly distributions of 
land vastly different in outline from those which now prevail. The pri- 
meval sediments were penetrated by outbursts of great volumes of igneous 
matter from the interior, the violence of which is made manifest by many 
clear evidences. Fractures in the crust of the earth, caused by earth- 
quakes that suddenly removed masses to positions far above or beneath 
their previous levels, were necessarily productive of such powerful trans- 
lations of water as abraded and destroyed solid materials, and spread them 
out over continents, or altogether swept them away, by operations infinitely 
surpassing any changes of which the historical era affords examples. 
I could here cite the works of many eminent writers for numerous evi- 
dences of the grander intensity of causation in former epochs, by which 
gigantic stratified masses were sometimes inverted, or so wrenched, broken, 
and twisted as to pass under the very rocks out of which they were formed. 
Among those who have passed away, I may mention de Saussure, von 
Buch, Humboldt, Cuvier, Brongniart, Buckland, Conybeare, De la Beche, 
and W. Hopkins. Of those who hold the same views and are now living, 
I may enumerate Elie de Beaumont, d'Archiac, de Yerneuil, Studer, Sedg- 
wick, J. Forbes, Phillips, Dana, Logan, and many others. The traveller 
amid the Alps and other mountain-chains will there see clear and un- 
mistakeable signs of such former catastrophes, each of which resulted from 
fractures utterly inexplicable by reference to any of those puny oscilla- 
tions of the earth which can be appealed to during historical times. 
On this point of the former intensity of causation, I must so far depart 
from the immediate object of this work, or the history of the successive 
Palaeozoic races, as to dwell briefly on some of those physical changes which 
have affected the surface at various periods in the whole range of geological 
succession. 
I may say that I never examined any extensive area without recogni- 
zing evidences of fracture, displacement, and occasionally inversion of the 
strata, which no amount of gradual, continuous action could possibly ex- 
plain. Thus, on the northern face of the Swiss and Bavarian Alps *, and 
occupying a range of hills upwards of 100 miles long, Miocene conglome- 
rates and shelly shales, which doubtless once reposed on Eocene beds, so 
abundant in the adjacent mountains, and which once dipped away into the 
lower grounds, are now seen to plunge at high angles under the very rocks 
on which they once rested, and from which they have been derived ; the 
intervening Eocene formation having entirely disappeared along this great 
line of fracture and inversion. 
See the deep chasm occupied by the Lake of the Four Cantons (between 
Brimnen and Altdorf ) — a profound transverse fissure, with vertical cliffs on 
either side, and observe the broken and discordant ends of the strata on the 
* See Quart. Journ. Geol. vol. v. pp. 188 &c. 
