G20 L.0.G Y. 
‘Nature of the Subject. 
We have most of us stood at the base of a great cliff, and looked 
upwards with awe at the rocks exposed on its weathered front. Such a 
sight might suggest many strange and interesting inquiries. How did 
these rocks come to be where they are? Of what are they composed ? 
When were they formed? Whence the material for the vast thickness of 
rock that composes the crust of the earth ? Whence have come the varied 
substances that form our limestones, coals, and sandstones? Whence also 
the strange shells, plants, and animals that a closer examination of their 
structure reveals? Are these the remains of bygone living organisms, or 
are they only marks in the rocks themselves? If they were once living 
creatures, what were their structure and habits? Such questions suggest 
themselves to every thinking person, whether man or boy, and such 
questions Geology undertakes to answer; and it is to the principles of 
this great science that we now proceed to direct attention. 
Geology, from the Greek ge, the earth, and logos, a description, is, 
according to its name, a description of the earth. It examines the 
various rocks that compose its crust, and seeks to explain their appear- 
ance, form, structure, relative position, formation, age, and distribution 
throughout the globe. It also inquires minutely into their contents, 
animal, vegetable, and physical; the causes of their imprisonment in 
their stony tombs; and the structure and habits of the creatures 
there found. It pictures forth the physical history of the globe 
during the successive epochs through which it has passed, with their 
varied scenery and inhabitants, the formation of its many strata, and 
the structure and progress of the organic forms that successively waved in 
its atmosphere, moved over its surface, or swam in its seas. In short, it 
is the province of Geology to describe the whole natural history of the 
globe during the various ages of the long past ; and it includes the zoology, 
