4 
The Quaternary Era, and its division in the Lafayette, 
Glacial, and Eecent Periods 
BY 
WARREN UPIIAM 
Contents : Limits of the Quaternary era. — Epeirogenic movements associated 
with glaciation. — Periods and epochs of Quaternary time. — The Lafayette 
period. — The Glacial period. — The Postglacial, Recent, or Présent period. 
— Estimated Duration of the Quaternary era. 
Limits of tue Quaternary Era. 
According to définitions in recent text-books of geology by 
Dana, Arcbibald Geikie, and Etheridge, the Quaternary era be- 
gan with the change frora the mild Pliocène climate to that ot 
the Glacial period, with its accumulation of vast sheets of laiid 
ice in high latitudes, and lias continued to the présent Unie. We 
are living in the Quaternary era, as thus defined, and it must 
extend far into the future to be at ail proportionate in length 
with the previous co-ordinate divisions of géologie time. Le 
Conte and Prestwich, however, consider the Quaternary division 
of time as cornpleted at the dawn of civilisation, with traditio- 
nal and written history ; and they assign recent géologie changes 
to a new era, named by Le Conte the Psychozoic, which is 
separated from the preceding principally on account of the su- 
premacy of man. The former view seerns préférable because 
man is known to hâve been contemporaneous with the Ice âge. 
Quaternary time therefore is here assumed to include : 1“ tlie 
period of changed conditions causing the accumulation of the 
ice-sheets ; 2“ the Glacial period, when the glacial and modified 
drift were formed ; and 3® the Postglacial, Recent, or Présent 
period, extending from the departure of the ice-sheets until now. 
