
TINDALE—SUBDIVISION OF PLEISTOCENE 625 
that during Pleistocene time periodic lowering of the earth’s temperature, through 
reductions of the amount of solar radiation received, brought about four major 
glaciations. During these glacial phases large iceeaps simultaneously formed at 
both poles of the earth. Water withdrawn from the oceans as ice was accumulated 
in the caps. Sea level dropped and low marine terraces, at present lying below 
sea level, were formed, Between each of these ice ages, each with its glacial 
“low tide,’’ there was a rise in temperature, aud following a period of retardation 
caused by the absorption of heat in the ice melt (a factor whose time value is not 
yet fully established) ice caps shrank, releasing water to the ocean; a rise in 
sea level resulted in an interglacial ‘high tide’? Subject to custatic modifications 
of sea level introduced by the sum total of world tectonic activity, and local 
deformations, the water rage in accordance with the degree of melting to form 
an interglacial high terrace. Evidence is that presetrt sea level is at some immediate 
position hetween such a glacial low and an interglacial high terrace phase. 
Presumptively there is a present trend towards the last-named phase. 
Zenner (1946) has published a further work on geochronology and its bearing 
on the development of man, This book had not come to hand in time for use in the 
preparation of this paper, 
Keble (1946) and Keble and Maepherson (1946), in stndies of specific 
terraces at Maribyrnong, and in Port Phillip Bay, stammarized recent work in 
Victoria on the subject of marine terraces, with a bibliography. In the course of 
disenssion Keble (1946, fig. 15) gave a correlation in which were included the two 
latest high terraces of Sonth Australia, and two late glacial stages in Tasmania. 
Tlis table, developed in the absence of Zenmer’s work, emphasizes the growing 
strength of evidence upon which the main outline of Pleistocene sequences is 
beginning to be based, Tis identifications depart principally from those of Zeuner 
in the placing of the Woakwine terrace as Wtirm 2/5 Tnterelacial, rather than as 
Riss-Wiitm Interglacial. 
rocker and B, CG. Cotton (1946) studied raised beaches in the Lower South 
Fast of South Australia, determining useful faunal associations for several 
terraces, They observed the identity of suites of terrace shell species with living 
faunas at other places. They seemed to regard this relationship as of primary 
significance iv determining the age of the terraces. On the possibly weak basis of 
eolour preservation of some shell fossils, the raised beach deposits were cousidered 
as of Recent and not Pleistocene ave, Their terraces were successive still stands 
of relatively brief duration on an unstable rising shore. Explanations in terms 
of tectonic warpings, rather than normal sea- and lake-shore processes, were used 
in detailing the development of lacustrine successions connected with present and 
immediate past shores. 
