23 
mantle (3), but did not produce adequate evidence to support his 
belief. Somerville has recently placed the matter beyond doubt 
(16), by recording and describing numerous features in the Perth 
District which are indisputable evidence of a recent displacement 
of the strand line, resulting in an apparent uplift of 23 feet from 
the present high water level. We considered that this movement 
should have been clearly recorded by the terraces of the Swan 
and Helena rivers, and, therefore, investigated the problem. Since 
the appearance of Daly’s suggestive papers (18, 19), recent uplift 
has assumed world-wide importance, and we have attempted to 
apply the results of our work as a test of Daly’s hypothesis. As 
great uncertainty now prevails in the use of the terms ‘‘elevation 
and subsidence of the land,” “displacement of the strand line,” and 
“eustatic movement of the ocean,”’ we shall use the term “rejuven- 
ating movement” when speaking of the recent changes of the Swan 
and Helena rivers. 
The Swan and Helena rivers, having terraces developed above 
the tidal limit, and raised beaches below it, are similar to the 
Aloonee River, Vie. (6), which has terraces associated with raised 
beaches. We suggest that the investigation of river terraces has 
an important bearing on the problem of eustatic movement. 
The Segments of the Swan River — - Somerville (16) has divided 
the lower Swan into convenient physiographic segments, each of 
which has fairly uniform features. To these we add two further 
segments. From Burswood to Guildford, the river flows through a 
wide valley, the sides of which are obscured by recent sand dunes. 
This segment is transitional in nature, for here the more evident 
features of the lower segments, which are due to the drowning (9, 
10), prior to the rejuvenating movements, give way to Matures 
usually ascribed to uplift. From Guildford to the foothills of the 
Darling escarpment, beyond Upper Swan, the river flows in a 
valley, which Jutson terms “precociously mature,” and exhibits all 
the characters of a river which has reached maturity after several 
successive rejuvenations. The Helena joins the Swan at Guildford 
and is similar to the Swan, from where it also emerges from the 
escarpment, but has a slightly sleeper gradient, and is, therefore, 
more juvenile. 
The Stean Coastal Plain — This prominent feature of the 
physiography of Western Australia has been adequately described 
by Jutson (10), in a broad way, while WoolnOugli has elaborated 
the description and recognises in it a series of distinct elements 
(13). We shall compare the features of rejuvenation existing in 
the Perth District with other features, further afield, which have 
not yet received detailed study, hut may reasonably be ascribed to 
the same causes, especially if Daly’s hypothesis be correct. The lakes 
marginal to the sea. between B unbury and Mandurah, form a pro- 
