HUNTINGTON AND GOLDTHWAIT: THE HURRICANE FAULT. 239 
is upheaval or depression accompanied by flexing, folding, or faulting. 
These movements begin and end slowly. They are of considerable dura- 
tion, and are varied by minor times of very rapid change or of almost 
complete quiet. Erosion proceeds as before, and is active or inactive in 
the normal fashion in proportion to the elevation of the country on 
which it works. As applied to the Plateau province, this view of earth 
movements is graphically illustrated in the last of the three diagrams in 
Figure 9. In this it is seen that since the end of the long Mesozoic 
period of deposition there have been three periods of uplift separated by 
longer periods of quiet. The former, however, were not continuous but 
were broken up into many episodes, when short periods of rest followed 
those of violent movement. Erosion continued unchecked at all times, 
but was divided into three distinct cycles. ; 
The initial stage of what Davis (c) has called a geographical cycle is a 
period of uplift during which erosion is revived and a region becomes 
young. The remaining stages of the cycle are carried to completion dur- 
ing the succeeding period of comparative rest. An ideal cycle involves 
not only the initial uplift whereby the country becomes young, but also 
a far longer time of little movement during which the relief passes 
through all the stages of maturity and is finally reduced to the feature- 
less peneplain of extreme old age. In another sense, however, the term 
cycle implies not the whole, but only a part of this long lapse of time. 
It is any period of erosion which begins in a movement of uplift and is 
brought to a close by another tectonic movement either of elevation 
whereby erosion is revived and a new cycle introduced, or of depression 
whereby erosion is brought to a standstill by the encroachment of the 
sea. Such interruptions may occur at any time, even in early youth, 
but the interval from the beginning of one to the beginning of another is 
stilla cycle. The word “cycle” is used in-a sense analogous to that of the 
word “‘life,’”’ and like it may be used in two distinct but complementary 
ways. Life in one signification is the complete existence of a normal 
organism during which it passes from infancy through youth, maturity, 
and old age to death. The life of man in this sense is seventy years. 
In another sense life is merely the actual period of existence of a specific 
organism. An animal whose life in the first sense of the word is fifty 
years, may die the day that it is born, but nevertheless we say that it 
has finished its life. A cycle in the first sense is ideal and can never be 
realized, since infinite time would be required to reduce any land mass 
to the condition analogous to death, that is, to a plain at absolute base- 
level. In the second sense any region that is subjected to erosion during 
