THE CLASSIFICATION OF FOSSIL PLANTS 
frequent, indications of climatic conditions during past 
ages. There is the mechanical work of glaciers, such as 
the piling up of moraines and the scratching of rocks. 
Soils are often preserved and show us whether the climate 
was dry or moist. In some instances we can reconstruct a 
topographical map of a geologic landscape, showing the 
distribution of mountains, rivers, lakes, and swamps. We 
can with great accuracy determine the seashore of various 
geologic horizons by the deposits of limestone and of 
shells of marine animals. All such indications taken to¬ 
gether present conclusive evidence of the climate of a 
region during any geologic period. 
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