THROUGH THE GEOLOGIST’S EYES 
Then, after a vast interval, there comes a break: 
something like an end and a new beginning, as if one 
day of creation were finished and a new one begun. 
The different formations lie unconformably upon 
each other, which means revolution of some sort. 
There has been a strike or a riot in the great mill, 
or it has lain idle for a long period, and when it has 
resumed, a different product is the result. Some- 
thing happened between each two layers. What? 
Though in remote geological ages the earth- 
building and earth-shaping forces were undoubtedly 
more active than they are now, and periods of de- 
formation and upheaval were more frequent, yet 
had we lived in any of those periods we should prob- 
ably have found the course of nature, certainly when 
measured by human generations, as even and tran- 
quil as we find it to-day. The great movements are 
so slow and gentle, for the most part, that we should 
not have been aware of them had we been on the 
spot. Once in a million or a half-million years there 
may have been terrific earthquakes and volcanic 
eruptions, such as seem to have taken place in Ter- 
tiary time, and at the end of the Paleozoic period. 
Yet the vast stretches of time between were evi- 
dently times of tranquillity. 
It is probable that the great glacial winter of 
Pleistocene times came on as gradually as our own 
winter, or through a long period of slowly falling 
temperature, and as it seems to have been many 
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