TIME DIVISIONS OF THE ICE AGE. 395 
of its extent was laid down as a gradually attenuated sheet ; 
that the ice retreated and the drift endured much subaerial 
erosion and denudation; that renewed accumulation and 
erowth of the ice-sheet, but mostly without extending to 
its earlier limits, were followed by a general depression of 
these burdened lands, after which the ice again retreated, 
apparently at a much faster rate than before, with great 
supplies of loess from the waters given off during its melting ; 
that moderate re-elevation ensued; and that during the 
farther retreat of the ice-sheet prominent morames were 
amassed in many irregular, but roughly parallel, belts, where 
the front at successive times paused or readvanced under 
secular variations in the prevailingly temperate and even 
warm climate, by which, between the times of formation otf 
the moraines, the ice was rapidly melting away. 
Such likeness in the sequence of glacial conditions 
undoubtedly implies contemporaneous stages in the glacia- 
tion of the two continents. It also seems to me more 
reasonably interpreted as a series of phases in the work of 
a single ice-sheet on each area than as records of several 
separated and independent epochs of glaciation, differing 
widely from one another in their methods of depositing drift. 
The latter view, however, is held by James Geikie, Penck, 
De Geer, and others in Europe; and it has been regarded as 
the more probable also for America by Chamberlin, Salisbury, 
MeGee, and others. 
Under this view Geikie has distinguished and named no 
less than eleven stages or epochs, glacial and interglacial.* 
These divisions of the Ice age are as follows: 1, The Scanian 
or first glacial epoch; 2, The Norfolkian or first interglacial 
epoch; 3, The Saxonian or second glacial epoch; 4, The 
Helvetian or second interglacial epoch; 5, The Polandian 
or third glacial epoch; 6, The Neudeckian or third inter- 
glacial epoch; 7, The Mecklenburgian or fourth glacial 
epoch; 8, The Lower Forestian or fourth interglacial epoch ; 
9, The Lower Turbarian or fifth glacial epoch; 10, The 
Upper Forestian or fifth interglacial epoch; and, 11, The 
Upper Turbarian or sixth glacial epoch. 
The earliest application of such geographic names to the 
* Journal of Geology, vol. iii, pp. 241-269, April-May, 1895. In the 
third edition of his Great Ice Age, the same time divisions had been 
recognized and fully described, but without distinctive names. 
