bottoms but makes much use of other evidence. Accord-
ing to Brooks the last glacial epoch lasted roughly from
30,000 to 18,000 B. C., but this includes a slight ameliora-
tion of climate followed by a readvance of the ice, known
as the Buhl stage. During the time of maximum glacia-
tion the British Isles stood twenty or thirty feet higher
than now and Scandinavia was "considerably" more
elevated. The author believes that this caused a fall of
1°C. in the temperature of the British Isles and of 2°C.
in Scandinavia. By an ingenious though not wholly con-
vincing method of calculation he concludes that this
lowering of temperature, aided by an increase in the area
of the lands, sufficed to start an ice sheet in Scandinavia.
The relatively small area of ice cooled the air and gave
rise to an area of high barometric pressure. This in turn
is supposed to have caused further expansion of the ice
and to have led to full-fledged glaciation.

About 18,000 B. C. the retreat of the ice began in good
earnest. Even though no evidence has yet been found,
Brooks believes there must have been a change in the dis-
tribution of land and sea to account for the diminution of
the ice. The ensuing millenniums formed the Magdale-
nian period in human history, the last stage of the Paleo-
lithic, when man lived in caves and reindeer were abun-
dant in central Europe. ² At first the ice retreated very
slowly and there were periods when for scores of years
the ice edge remained stationary or even readvanced.
About 10,000 B. C. the edge of the ice lay along the
southern coast of Sweden. During the next 2000 years it
withdrew more rapidly to about 59°N. Then came the
Fennoscandian pause, or Gschnitz stage, when for about

-216-