ELEMENTARY GEOLOGY 
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CHAPTER I 
INTRODUCTION 
Tue earth has always furnished an interesting theme 
for the minds of thinking men. Speculations concern- 
ing its origin and history are found in the writings of 
philosophers and scientists of all times. The ancients 
pursued the study with considerable success. ‘Then 
elapsed many ages during which almost no progress 
was made. A hundred years ago there was hardly 
more knowledge of the history of the earth than had 
been possessed by the ancient Greeks. 
Within this century, and indeed almost within the 
last half of it, the science of Geology, or Earth History, 
has been developed. Even now the story of the earth 
is but partly known, and in portions of the world, there 
are bodies of men who are devoting their lives to the 
fascinating work of reading from the rocks the secrets 
which are engraved on them. ‘The rocks are the pages 
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