
TINDALE—SUBDIVISION OF PLEISTOCENE 623 
have observed at the same elevation throughout Tasmania. This, his Malanna 
Glacial Stage, was the first low water phase of the Pleistocene, there being, accord- 
ing to hint, no evidence of any pre-Malannau low water phase. Roughly, contem- 
poraneously flooding of the low lands occurred all round the coastline of Tasmania. 
Both the emergence and the flooding were seemingly expressions of eustatic 
variations of sea level; the emergence began with his first glacial (Malannan) 
and the fooding during a subsequent interglacial (the Millbrook Rise), Lewis 
identified as of Malannan date a trough in the River Derwent estuary which 
extends to 150 feet (—45 metres) below present sea level, giving au indication of a 
possible minimum condition of the lowering of sea level during his Malannan times. 
He found little or no evidence of differential movement such as could be assigned 
to a post-glacial (i.e. Post-Malannan) isostatie recovery from ice loading (as 
postulated by David, 1924), but implied some movement was due to tectonic 
activity on a veyional seale. During his Millbrook Stage river fravels were 
deposited to an average height of 150 feet (45 metres) above present sea level. 
Subsequent to the Millbrook phase, which is specifically maintained as 
embracing the ‘longest of the Tasmanian interglacial periods,’’ Lewis placed a 
younger, and lesser, Yolande glaciation wloch, he concluded, appeared m two 
distinet phases, separated by an interglacial interval. Associated with the Yolande 
glacials was a shoreline identified as approximately 60-80 feet (—18 to 25 metres) 
below present sea level. Following the Yolande ylacials came an interglacial 
phase characterized by the 15 feet (4:5 metres) raised beaches first recorded by 
Darwin (1876) at Ralph Bay. Lewis states that the Ralph Bay terrace is a 
vniversal feature of Tasmania, extendiug impartially iu elif! faces exposed to 
heavy seas and in estuaries where waves never occur, Following the Ralph Bay 
interglacial came the Margaret Glacial, less extensive than either Yolande or 
Malannan glacials and affecting only mountain arcas, down to 2,200 feet in 
western Tasmania and to 3,700 feet in the east. 
Associated with Margaret Glacial times was a low water phase which 
permitted present day streams to cut channels down to 15-21 feet (4:5 to 
-6-5 metres) below present sea level, exposing sections of Ralph Bay Stage 
terraces, Other than this evidence there was little conelusive data to show that 
Margaret glaciers were not retreat features of the greater Yolande glaciations, 
Lewis decided, on the general appearances of freshness, that Margaret glaciers 
existed at a period far closer to the present day than the time interval between 
Yolande ice and the Margaret ice, 
Lewis did not make any suggestions for direct correlation with glaciations 
elsewhere. 
Zener (1935, 1942, 1945) in a series of papers culminating in a monographie 
