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WITH CERTAIN EXTINCT QUADRUPEDS. ose 
that the primitive people to whom we attribute the hatchets and 
other worked flints of Amiens and Abbeville might have communi- 
cated with the existing land of England by dry land, inasmuch as 
the separation did not take place until after the deposit of the rolled 
diluvial pebbles, from among which the hatechets and worked flints 
have been collected. On the other hand, M. Elie de Beaumont 
having assigned the production of the erratic phenomena existing in 
our valleys to the last dislocation of the Alps, we should be author- 
ized to conclude from this second hypothesis, that the worked flints 
carried along with the pebbles in that erratic deposit in the bottom 
of the valleys afford a proof of the existence of Man at an epoch 
when Central Europe had not yet reached ;the completion of its 
present great orographic relief. 
While it has been held that no change has taken place in the great 
lines of level since the formation of the erratic deposits in the lower 
parts of our valleys, and although such changes cannot be distinctly 
traced in the central parts of the continents, from the absence of 
standards of comparison, they are not the less easy to be recognised 
as having occurred, even since the existence of Man, throughout the 
whole extent of the European coasts, from the Gulf of Bothnia to the 
very eastern extremity of the Mediterranean. They have been ob- 
served by different authors on a considerable number of points of the 
coast, where they have verified the existence of objects of human 
industry in deposits of marine origin, raised up at different elevations 
above the sea-level. Such changes, be they the result of action more 
or less violent, of movements more or less sudden, have not amounted 
to catastrophes so general as to affect to a sensible degree the regular 
succession of organized beings. 
We find incontestible proof of this in the British Islands, whither 
the most considerable number of terrestrial species must necessarily 
have immigrated prior to the separation of those islands from the 
Continent, and where they have established themselves and have 
continued by successive generations to the present day. The same 
thing has occurred on the Continent, where the same terrestrial fauna 
has continued without any other modification than the geographical 
displacement of certain species and the final disappearance of some 
others—disappearances that have resulted, not from a simultaneous 
destruction, but rather from a series of successive extinctions which 
appear to have been equally gradual as regards space and time. 
