INTRODUCTION. 
XVII 
time, but belonged to many different periods of the earth’s 
history. Their destruction and burial, therefore, could not 
be ascribed to any single great catastrophe. It was demon¬ 
strated that during past ages the distribution of land and 
sea, mountains and plains, had frequently changed—that, in 
fact, rain, rivers, waves, currents, volcanoes, and phenomena 
like earthquakes, were continually altering the earth’s 
surface, even under the eyes of man himself. The fossils 
were proved in most cases to be buried in displaced portions 
of sea-bottom, and in the mud of dried-up lakes; and it was 
realised that the relative ages of these deposits could be 
determined by the order in which they lay one upon 
another. Thus arose the true “ science of the earth,” which 
was named Geology by De Luc in 1778. 
An English civil engineer, William Smith (1769-1839), 
was perhaps the first to realise fully the possibilities of this 
new branch of learning. His profession necessitated much 
travel through the country, and his interest in the distri¬ 
bution of fossils in the different kinds of rock led him to 
make a large collection, which was acquired by the British 
Museum in 1816, and is now exhibited in Gallery No. 11 
of the Department of Geology. His published maps and 
writings prove that the various features of the landscape, 
in districts where fossils occur, are naturally carved out of 
layers of rock, which are simply old sea-beds or lake-beds 
piled one upon another, the oldest at the bottom, the newest 
at the top, each containing its own definite and invariable 
set of fossils. They also show that in most cases when these 
old sediments were raised into dry land, they were tilted in 
various ways from their originally horizontal position; so 
that it is often possible in a short walk to pass over the cut 
edges of many successive layers, perhaps hundreds of feet in 
thickness, representing immense periods of time. 
While Smith and others were busily engaged in collecting 
fossils and observing their distribution, Blumenbach, Cuvier, 
Lamarck, Brongniart, and other naturalists were occupied 
with a detailed study of the fossils themselves. They soon 
demonstrated that, while most of these petrified remains 
could be interpreted by comparing them with the life of the 
present world, a large proportion represented animals and 
plants no longer existing. They also observed that the 
older the fossils, the more strikingly different they were 
from any animals and plants now living. It therefore 
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