238 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
ter-fault cycle of erosion, just before the beginning of the last great 
faulting. 
The exigencies of language and the necessity of brevity often oblige 
us to speak of periods of faulting and folding as though they were dis- 
tinct from those of erosion. According to the old cataclysmic idea, this 
was indeed the case. We may illustrate this graphically by a diagram 
in which the course of time is represented by horizontal distance, while 
the relation of any given stratum to sea-level is represented by vertical 
distance. The cataclysmic theory supposed that periods of uplift or 
other tectonic movement were so sudden and paroxysmal that in such 
Figure 9. 
Diagrammatic scheme of cycles. 1, Pure cataclysmic view; 2, Pure uniformitarian view; 
38, Eclectic view. 
a diagram (Fig. 9) they might fairly be represented as vertical lines, 
since the time element involved was thought to be negligible. A simi- 
lar diagram representing the opposite or uniformitarian view shows 
absolutely no vertical lines, and relatively few that are perfectly hori- 
zontal. Changes were supposed to take place so slowly that there was 
comparatively little chance for absolute rest, and none whatever for 
sudden transformations. The modern or eclectic view is a combination 
of these two. It supposes the existence of distinct periods of essential 
rest separated by longer or shorter periods of unrest, during which there 
