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INTRODUCTION. 
became evident that fossils afforded a means of discovering 
the past history of life on the earth—of determining the 
gradual stages by which our present animals and plants 
have become what they are, and have assumed their present 
geographical distribution. Thus was attained the “ science 
of ancient life,” which was named Palaeontology by 
H. D. de Blainville and Fischer von Waldheim ip 1834. 
The Department of Geology in the British Museum 
chiefly deals with fossils from the latter point of view, and 
attempts to explain the main features in the life of the 
Present by reference to that of the Past. 
Note to the Geological Time-scale .—The names in the three columns 
to the left are applied only to periods of time. The names in the two 
columns on the right are those of actual strata deposited during the time- 
periods opposite which they are placed. These strata or rock-groups are 
only a few out of the many that might have been mentioned, and it must 
not be inferred that those in the European column are the precise 
equivalents of those next them in the British column. It is just because 
rock-formations in different parts of the world so rarely are equivalent, 
that a time-scale is needed to which each can be referred. The absolute 
duration of the divisions on the time-scale is a matter of pure conjecture ; 
but their relative duration can be roughly estimated from the thickness 
of the rocks. An attempt is made to represent this relative duration by 
the diagram to the right, which is based on the thickness of the rocks in 
N.W. Europe. 
