16 
Proceedings of the Royal Society of Edinburgh. [Sess. 
deposition of the overlying series, and by the accumulation of peat, soils, 
sands, and gravels between successive drift sheets. 
The detailed classification advanced by Chamberlin and Salisbury is 
given below ( Text Book of Geology, 1906) : — 
XIII. The Champlain sub-stage (marine). 
XII. The Glacio-lacustrine sub-stage. 
XI. The Later Wisconsin, the Sixth Glacial Advance. 
X. The Fifth Interval of Deglaciation. 
IX. The Earlier Wisconsin, the Fifth Glacial Invasion. 
YIII. The Peorian, the Fourth Interglacial Interval. 
VII. The Iowan, the Fourth Invasion of the Ice. 
VI. The Sangamon, the Third Interglacial Interval. 
V. The Illinoian, the Third Glacial Invasion. 
IY. The Yarmouth, the Second Interglacial Interval. 
III. The Kansan or Second Glacial Invasion. 
II. The Aftonian, the First Interglacial Interval. 
I. The Jerseyan, the First Glacial Advance. 
Pirrson and Schuchert ( Text Book of Geology, 1915) give the following 
table of divisions of Pleistocene time in North America, based on the 
researches of Chamberlin and Salisbury, and 0. P. Hay : — 
Post-glacial or present time 
Vanishing of ice-sheets. Champlain marine invasion. 
Lowering of water-level of Great Lakes. Gradual 
amelioration of climate. Gradual extinction of elephants, 
mastodons, Megalonyx , musk-oxen, etc. 
Fifth or Wisconsin Glacial 
Stage 
Wiirm Stage in Europe 
Fourth or Peorian Interglacial Record not well determined. Formation of peat beds and 
Stage soils. Wide distribution of loess. 
} Spread of ice-sheets and drift. Fauna and flora driven 
south. 
Fourth or Iowan Glacial Stage Spread of ice-sheets and drift. Record not well determined. 
Third or Sangamon Inter- Accumulation of peats, soils, and loess. Horses, elephants, 
glacial Stage mastodons, bison, peccaries, and tapirs probably present. 
Third or Illinoian Glacial 
Stage 
Riss Stage in Europe 
Spread of ice-sheets and drift. Deposition of loess. 
Apparently 60 per cent, of present land fauna then 
living. Mastodons, mammoths, horses, tapirs, bison, 
deer, and sabre-tooth tigers. 
Second or Yarmouth Inter- Formation of peats, soils, and bluish loess. Animals about 
glacial Stage as in Illinoian stage. 
Second or Kansan Glacial ^ gp rea( j 0 f icg.^eets and drift. Extinction of certain 
Mindel Stage in Europe J camels and horses. 
r Great* abundance of mylodons, megatheres, Megalonyx , 
First or Aftonian Interglacial | mastodons, elephants (3 species), horses (6 species), 
Stage ' camels (4 species), sabre-tooth tigers, bears, etc. A warm- 
l temperate fauna. 
First or sub-Aftonian Glacial Spread of ice-sheets and drift. Includes pre-Kansan, 
Stage Nebraskan, and Albertan drifts. 
