IOS EVOLUTION OF LIFE. 
are composed being easily distinguishable, the convulsions 
to which others have been subjected have been so great, 
and the effects of heat so intense, that no sign of such 
stratification is visible, if it ever existed. The old Geologists 
resembled the knights who fought about the color of the 
shield. The early German school, influenced by the char- 
acter of the rocks in that part of the world, attributed a 
great deal to the action of water; while the Scotch school, 
equally impressed by the features of the formations in their 
country, attached great importance to the effects of heat. 
Hence arose the sects of the Neptunists and Plutonists. 
Both were right in attributing the formation of the rocks 
in their respective countries to the action of water and heat. 
Both were wrong in applying to the whole world conclu- 
sions drawn from such local data. Modern Geologists 
steer a middle course,—avoiding these extremes,—consider- 
ing the effects of the combined action of water and heat, 
as well as admitting the influence exerted by these agents 
separately. Rocks the origin of which is supposed to be 
due to the gradual deposition under water, in layers or 
strata, of the materials composing such formations, are called 
Aqueous Rocks; while those of which the structure clearly 
testifies to the action of heat in producing them are known 
as Plutonic Rocks. Finally, the Metamorphic Rocks illus- 
trate the alternate action of water and heat. Geologists 
classify rocks according to their mineral composition, their 
organic remains, and the order in which they follow or 
overlie one another. The Geologist, starting in Canada, 
and traveling through New York and Pennsylvania, notices 
continually as he advances southward the change in t 
— 
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minerals composing the rocks, and the different aspects of 
their organic remains. Thus, in Canada and the east of 
New York, granite, gneiss, and syenite are common minerals. 
These rocks were originally called Azoic, or without life; 
improperly, however, as within a few years the Eozoon, or 
successive 
very evide 
each other 
Marine rem 
of New Yo 
age, are c; 
which they 
New Jerse 
