THE LAWS OF GEOLOGICAL ACTION. 5 
wonder at the former general acceptance of Catastrophistic 
doctrines. Even in the light of our present widely-increased 
knowledge, the series of geological monuments remains a broken 
and imperfect one ; nor can we ever hope to fill up completely 
the numerous gaps with which the geological record is defaced. 
Catastrophism was the natural method of accounting for these 
gaps, and, as we shall see, it possesses a basis of truth. At 
present, however, catastrophism may be said to be nearly ex- 
tinct, and its place is taken by the modern doctrine of ‘ Con- 
tinuity ” or “‘ Uniformity ””—a doctrine with which the name of 
Lyell must ever remain imperishably associated. 
The fundamental thesis of the doctrine of Uniformity is, 
that, in spite of all apparent violations of continuity, the se- 
quence of geological phenomena has in reality been a regular 
and uninterrupted one; and that the vast changes which can 
be shown to have passed over the earth in former periods have 
been the result of the slow and ceaseless working of the ordi- 
nary physical forces—acting with no greater intensity than they 
do now, but acting through enormously prolonged periods. 
The essential element in the theory of Continuity is to be found 
in the allotment of indefinite time for the accomplishment of 
the known series of geological changes. It is obviously the 
case, namely, that there are two possible explanations of all 
phenomena which lie so far concealed in “the dark backward 
and abysm of time,” that we can have no direct knowledge of 
the manner in which they were produced. We may, on the 
one hand, suppose them to be the result of some very powerful 
cause, acting through a short period of time. ‘That is Catas- 
trophism. Or, we may suppose them to be caused by a much 
weaker force operating through a proportionately prolonged 
period. ‘This is the viewof the Uniformitarians. It is a ques- 
tion of exergy versus ¢ime ; and it is “2me which is the true ele- 
ment of the case. An earthquake may remove a mountain in 
the course of a few seconds; but the dropping of the gentle 
rain will do the same, if we extend its operations over a millen- 
nium. And this is true of all agencies which are now at work, 
or ever have been at work, upon our planet. ‘The Catastro- 
phists, believing that the globe is but, as it were, the birth of 
yesterday, were driven of necessity to the conclusion that its 
history had been checkered by the intermittent action of par- 
oxysmal and almost inconceivably potent forces. The Unifor- 
mitarians, on the other hand, maintaining the “ adequacy of 
existing causes,” and denying that the known physical forces 
ever acted in past time with greater intensity than they do at 
present, are, equally of necessity, driven to the conclusion that 
