THE USES OF FOSSILS 393 
sketch, and eagerly seek for more knowledge. The 
story is one of constant change and of general prog- 
ress from lower to higher forms of life. Strange ani- 
mals and plants have come upon the earth, and after 
altering in form and nature, have disappeared, while 
their place has been taken by others; and always, as 
a result of these changes, there has been a general 
evolution and advance. 
Uses of Fossils. — The chief use of fossils is found 
in the hints that they give us concerning the climate 
and physical geography of the past, in the evidences 
that they furnish of evolution, and in their value in 
the construction of the geological time-scale or chro- 
nology. 
Climate. Fossils tell us much of importance con- 
cerning the climate of bygone ages. Frozen in the 
earth of Siberia we find bodies of the mammoth, which 
in many respects was like the elephant, though it 
had a covering of hair for protection from the cold. 
The presence of these animals tells us that at one time 
the climate of this bleak land was less severe. 
Far to the north, within the Arctic circle, and directly 
beneath the fields of perpetual ice, the rocks contain 
fossils of animals and plants which are now confined 
to more temperate zones. There are evidences that 
changes from warm to cold, and the reverse, have 
alternated in the ages of the past. 
