more elevated shell beds and shore lines belong to the preceding 
cycle, but this cannot be demonstrated without careful levelling. 
The Rottnest shell banks are as important in our local geology 
as are the Perth shell banks. Shells from the Kottnest banks have 
also been examined by Mr. Medley, who states that they belong u> 
existing genera, and indicate a climate similar to the present one 
of t lie locality, whereas those of the Perth banks indicate warmer 
conditions. The closure of the lakes, and the union of two or 
perhaps three islands to Form the present Kottnest may he assigned 
to the close of the Helena cycle or to the opening' of the Present 
period. The striking fact for the visitor is that the undercut 
cliffs of (he salt lakes belong eharlv to Helena times, while those 
of the sea shores belong equally clearly to the present period. In 
the absence of careful levelling*, confusion also exists concerning the 
“raised reefs” and “raised’’ beaches of the present sea shores, which 
belong to the borderline between the two cycles. The existing 
reef platforms and the undercut shores of course are definitely pro- 
ducts of very recent action. 
“Uplift” has been demonstrated at widely separated places 
on the shores of the Swan Coaxial Slain, but it is not our intention 
to deal with regional movement here. The whole question of re- 
cent “uplift” around the shores off Australia shall be reviewed by 
one of us (M.A.) shortly. The lakes marginal to the sea, between 
Bunbury and Miindutali, have been mentioned on a previous page, 
and shall he considered briefly. Leschenault Tibet, Lake Preston, 
the Martin Tank line of lakes and swamps, and Lake (Tilton are 
long, narrow sheets of water arranged in echelon parallel to the 
coast. Leschenault Inlet is connected with the sea. Lake Preston 
is not, and is saline, and is associated with a development of the 
Kottnest shell banks. The Martin Tank line has an elevation 
of about 3f) feet above sea level and is associated with a develop- 
ment of the Perth shell banks ( fide Mr. A. K, Mitchell, B.Sc.). 
Lake CTiftcn, still further inland, stands about 60 feet above sea 
level. The sequence of events in this area seems to have been 
similar to that of the Swan River District* with this exception: 
that instead of a cycle of drowning prior to the rejuvenating 
movements there was here an actual uplift in pre-Guildford times, 
which elevated Lake (Tift on. The Martin Tank line, with the 
associated Perth shell banks* are interpreted as the product of the 
Guildford cycle. Their present height above sea level is not in ac- 
cordance with eiistatie movement unless it be assumed that the 
movement of uplift was also still in progress. Lake Preston 
and its Kottnest shell banks we assign to the Helena cycle, and 
Leschenault Inlet to the Present period. We suggest that eacli 
of these lakes has been closed and rendered saline b\ processes 
similar to those which operated on the lakes of Kottnest Island. 
