DEVELOPMENT AND DISTRIBUTION OF THE LEGUMINOSAE. 357 
Great Ice Age of Post-Tertiary time. This period has 
just disappeared. Great mountain ranges were formed 
also, either during, or at the close of, both the Miocene 
and Pliocene Periods. 
In Australia the land appears to have been worn down 
to a low-lying surface towards the close of the Cretaceous, 
and much of the area so worn down was of barren sandy, 
or hungry clay, nature. During the Tertiary the eastern 
side of the continent had been elevated by stages to its 
variable height, and the waste from the plateaus so 
formed was carried, in part, by the inland drainage to form 
the rich soils of the great plains of the interior. These 
inland plains are therefore relatively recent in age. 
South Africa also, during later geological time, appears 
to have been elevated to forma great plateau. Southern 
New Zealand also, in the closing Tertiary, appears to have 
been elevated to form high plateaus. 
The Pleistocene Ice Age arose from a general lowering 
of temperature throughout the world. 
Messrs. David, Pittman, and Helms’ have also demon- 
strated a Pleistocene glaciation for the Kosciusko Plateau 
of Australia. 
Summary.—The geological records of Cretaceous and 
Post-Cretaceous time suggest that there was a luxuriant 
vegetation both in Upper Cretaceous and Hocene time, 
with xerophytic forms confined to barren, sandy and hungry 
dry areas relatively limited in extent. A gradual contrac- 
tion of areas of moist and mild climate is indicated for the 
Post-EKocene, with a concomitant increase in the develop- 
ment of xerophytes in the world, especially in either 
exposed subarid, or sandy, areas such as Australia, South 
Africa, and the steppes of Kurasia. The Post-Tertiary 
1 (27). 
