53 



l)eing so, and given the southern hemisphere its maximinn of 

 cold and the high latitudinal position of the sun in the northern 

 hemisphere, it follows that the system of trade winds in the 

 southern hemisphere is shifted further north, and with it those 

 other effects which are correlative, bringing our southern 

 shores into the region of copious summer rains, and Central 

 Australia within that of winter rains. More than this, the 

 dry belt would be shifted so far to the north as to be almost 

 obliterated, or, at least, greatly narrowed by its proximity to 

 oceanic waters. 



Under such influences the climate of Southern Australia is 

 changed in a way not hitherto foreseen, and the question, did 

 perennial ice exist on its mountains ? is not so difficult to 

 answer. By induction w^e should have been led to anticipate 

 the discovery of those glacier signs, the interpretation of which 

 has created so much unnecessary controversy. 



A glacial period and a pluvial period mean the same to me, 

 being referrible to the same cause — rain or snow — according 

 to latitude or elevation. 



I have persistently argued for some years that the rainfall 

 has greatly diminished since the Pliocene period, the evidences 

 of which are more striking in Central Australia than in more 

 southern latitudes because of the present poverty of rain 

 there. 



A vastly increased rainfall over what is now the arid region 

 of Australia in former times is demanded by the extinct rivers 

 and lakes and the former existence of large herbivores. 



1. The Extij^ct Rivers. — All the watercourses which origi- 

 nate within the dry belt are characterised by the absence of water. 

 It is only towards their sources that they collect the surface 

 drainage, and then only at distant intervals of time. Many of 

 them are of great width and are traceable for more than 100 

 miles to the depressed area around Lake Eyre, where they be- 

 come obliterated many miles from the 23resent shore. The 

 Paroo and other of the north-western tributaries of the Darling 

 no longer carry water in their lower sections. The volume of 

 discharge from the Eiver Murray must have been many times 

 greater than now. (See my paper on the Eiver Murray, p. 30, 

 et, seq., vol. YII. of these Trausactions). 



2. Extinct Lakes. — Lake Eyre is the centre of the conti- 

 nental drainage, and is maintained at the present time by the 

 flood-waters of the Cooper and Diamantina, which are supplied 

 by tropical rains. But toward this extensive depression there 

 are directed many dry river-beds, whilst hundreds of square miles 

 around the present lake margin are covered with sandhills, 

 separated by loamy interspaces, which are littoral sandbanks 

 marking the successive stages in the contraction of the water 



