130 THE DOCTRINE OF DESCENT. 
Even after the appearance of Lyell’s “Principles of 
Geology,” the hypothesis of catastrophes received its 
special completion by Elie de Beaumont’s theory of the 
structure and genesis of mountain chains. From the 
first, however, Lyell interposed, and derived the following 
conclusion from a comparison of the slow but continued 
and perceptible upheavals and subsidences occurring 
in historic times, with the various modifications which 
organisms had meanwhile undergone. “In a word, the 
movement of the inorganic world is obvious and pal- 
pable, and might be likened to the minute-hand of a 
clock, the progress of which can be seen and heard; 
whereas the fluctuations of the living creation are 
nearly invisible, and resemble the motion of the hour- 
hand of a time-piece. It is only by watching it atten- 
tively for some time, and comparing its relative position 
after an interval, that we can prove the reality of its 
motion.” 
Careful observation and logical deduction had thus 
arrived at conclusions diametrically opposite to the 
assertions of Cuvier, who inferred the geological catas- 
trophes mainly from the striking difference of successive 
organisms, While botanists and zoologists prosecuted 
their studies on Cuvier’s system, Geology was being 
metamorphosed under the hands of Lyell and his adhe- 
rents. He proceeded from the most tangible basis. 
That it rained during the era of the coal formation, as 
it now rains, may be seen by the impress of rain-drops 
on the levels of that formation. The actions of rivers, 
the sediments of deltas, previously neglected, were now 
studied, and likewise the colossal mud deposits, such as 
are exhibited by the Nile and the Amazon, and also the 
