eh. i.] 
METHODS OF THEORIZING IN GEOLOGY. 
relative level of sea and land, and doubts were then entertained 
whether this change might be accounted for by the partial 
drying up of the ocean, or by the elevation of the solid land. 
The former hypothesis, although afterwards abandoned by 
general consent, was at first embraced by a vast majority. A 
multitude of ingenious speculations were hazarded to show 
how the level of the ocean might have been depressed, and 
when these theories had all failed, the inquiry, as to what 
vicissitudes of this nature might now be taking place, was, as 
usual, resorted to in the last instance. The question was agi- 
tated, whether any changes in the level of sea and land had 
occurred during the historical period, and, by patient research, 
it was soon discovered that considerable tracts of land had 
been permanently elevated and depressed, while the level of 
the ocean remained unaltered. It was therefore necessary to 
reverse the doctrine which had acquired so much popularity, 
and the unexpected solution of a problem at first regarded as 
so enigmatical, gave perhaps the strongest stimulus ever yet 
afforded to investigate the ordinary operations of nature. For 
it must have appeared almost as improbable to the earlier geolo- 
gists, that the laws of earthquakes should one day throw light 
on the origin of mountains, as it must to the first astronomers, 
that the fall of an apple should assist in explaining the motions 
of the moon. 
Of late years the points of discussion in geology have been 
transferred to new questions, and those, for the most part, of 
a higher and more general nature ; but, notwithstanding the 
repeated warnings of experience, the ancient method of philo- 
sophising has not been materially modified. 
We are now, for the most part, agreed as to what rocks are 
of igneous, and what of aqueous origin, — in what manner fossil 
shells, whether of the sea or of lakes, have been imbedded in 
strata, — how sand may have been converted into sandstone, — 
and are unanimous as to other propositions which are not of a 
complicated nature ; but when we ascend to those of a higher 
order, we find as little disposition, as formerly, to make a strenu- 
ous effort, in the first instance, to search out an explanation in 
