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the one hand, while the whole Tertiary or Kainozoic, up to the present day, 
is one great geological period, characterised by a continuous though gradually 
changing fauna and series of physical conditions, and there is, consequently, 
no good basis for setting apart, as some geologists do, a Quaternary as 
distinct from the Tertiary period, on the other hand there is a distinct phy- 
sical break between the Pleistocene and the Modern in the great glacial age. 
This in its arctic climate and enormous submergence of the land, though it 
did not exterminate the fauna of the Northern Hemisphere, greatly reduced 
it, and at the close of this age many new forms came in. For this reason 
the division should be made, not where Dawkins makes it, but at or about 
the end of his ‘ Mid-Pleistocene.’ The natural division would thus be : — 
I. Pleistocene, including — 
(a) Early Pleistocene , or First Continental period. Land very extensive, 
moderate climate. 
(b) Later Pleistocene, or glacial, including Dawkins’s ‘ Mid Pleistocene.’ 
Tn this there was a great prevalence of cold and glacial conditions, and a 
great submergence of the northern land. 
II. Modern, or period of Man and Modern Mammals, including — 
(a) Post-glacial, or Second Continental period, in which the land 
■was again very extensive, and Paloeocosmic man was contemporary with 
some great mammals, as the mammoth, now extinct, and the area of land in 
the Northern Hemisphere was greater than at present. This represents the 
Late Pleistocene of Dawkins. It was terminated by a great and very general 
subsidence accompanied by the disappearance of Pakeocosmic man and some 
large mammalia, which may be identical with the historical deluge. 
(i b ) Recent, when the continents attained their present levels, existing 
races of men colonised Europe, and living species of mammals. This includes 
both the Prehistoric and Historic periods. 
On geological grounds the above should clearly be our arrangement, 
though, of course, there need be no objection to such other subdivisions 
of the Recent Period into local Historic and Pre-Historic ages as 
historians and antiquaries may find desirable for their purposes. On this 
classification the earliest certain indications of the 'presence of man in Europe , 
Asia, or America, so far as yet known, belong to the Modern period alone. 
That man may have existed previously no one need deny, but no one can 
positively affirm on any ground of actual fact.’ 
It will be observed that a consideration of the distribution of the post- 
glacial gravels, the character and extent of the post-glacial denudation, and 
the faunal changes between the post-glacial and the recent periods, lead me 
to infer that a submergence of the land occurred at the close of the post- 
glacial period, and that it is not improbable that this submergence may have 
