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continents not in some way increased, they would be altogether 
washed away in time. A few million of years would suffice to 
distribute the material which now stands above water over the 
sea so that a somewhat shallow ocean would cover the globe. 
Instead we find that the Pacific slope has actually grown, and 
that vast areas once covered by water are now dry land. Either 
the actual amount of material between the surface of this area 
and the earth’s centre has been increased by subterranean transfer, 
or else this material has increased more in volume by an amount 
almost incredibly great. It now stands at an average level of per¬ 
haps 3,000 feet above the sea, and many other thousands of feet 
must have been removed by erosion. I can give you no theory of 
this strange phenomenon. It is one of the aspects of the great 
problem of upheaval and subsidence which it is the dream of 
many a geologist to solve. 
The mountain system of the Pacific slope is most intimately 
connected with the great lines of upheaval to which I have called 
attention. Every one of them is now marked by mountain ranges 
and the most important ranges of the region—the Wahsatch, the 
Sierra Nevada and the coast ranges of California, the Cascades 
and the Blue Mountains—coincide in position with the main sys¬ 
tem of faults. Of all the chief lines of fault only that crossing the 
fortieth parallel at 117 0 is not marked by a mountain range of 
great importance. 
It would be easy to show, were there time to do so this evening, 
that lines of faulting and mountain ranges are two effects of a 
single cause and that they should be expected to appear in com¬ 
pany. Lines of faulting, however, are permanent; while moun¬ 
tain ranges arc, geologically speaking, evanescent. Thus I men¬ 
tioned a movement on the great Wahsatch fault which occurred 
in the Archaean. Renewed movement took place on the same 
line at the end of the Cretaceous on an enormous scale, and no 
doubt small motions have been frequent. The last is so recent 
that vegetation has not had time to clothe the scarp. The inter¬ 
val of time since the first of these movements is perhaps 50,000,000 
years, time enough for the process of degradation to remove many 
a range of the size ot the Wahsatch. So too there is evidence 
that the Sierra Nevada has received accessions from beneath 
