402 APPENDIX. 



objectionable. Even in Europe, the historic age of the 

 south is altogether a different thing from that of the np^th; 

 and to speak of the pre-historic period in Greece .and in 

 Britain or Norway as indicating the same portion of time 

 is altogether illusory. Hence a large portion of the dis- 

 cussion of this subject has to be called by our author '* the 

 overlap of history." Further, the mere accident of the 

 presence or absence of historical documents cannot con- 

 stitute a geological period comparable with such periods 

 as the Pleistocene and Pliocene, and the assumption of such 

 a criterion of time merely confuses our ideas. On the one 

 hand, while the whole Tertiary or Kainozoic, up to the 

 present day, is one great geological period, characterized 

 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 physical 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 were 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 ex- 

 tensive, moderate climate. 



(6) Later Pleistocene, or glacial, including Dawkins' " Mid Pleis- 

 tocene." In this there was a great prevalence of cold and glacial con- 

 ditions, 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 Paleocosmic man was contemporary 

 with some great mammals,— as the mammoth, now extinct,— and th<j 



