132 . 
S.A. NAT., VOL. XIV. 
The Coast from Outer Uarbour to Sellicks Hill. Auoust 31st. 193T.. 
lower and were built in sweeping curves as shown In the plan. 
Le Fevre Peninsula is growing towards the north, following 
the curve of the Port River as the latter cuts into the narrow 
extension of Torrens Island, a feature that must some day com- 
pleteh’ disappear. 
J'lie rapid way in which sand dunes and muds will silt up 
auiet areas has been shown in a remarkable manner in the sea ad- 
joining the artificial projection on wTich Outer Harbour is built. 
Sixteen years ago blue water filled both these angles. To-day 
both the northern and southern bays adjoining Outer Harbour- 
are almost completely silted up, and the differences in the type 
of silniig of the two bays are as interesting as the similarities; 
these features are left for the reader to investigate. 
Older Sand Dunes. — In the long history of the l)uilding 
up of the Adelaide Plains there have been many lines of sand- 
dunes of which every trace has completely disappeared. But 
there is one series of ancient dunes of which a large portion still 
remains and fulfils an important part in the economics of the 
area. These are the older sand-dunes, mostly reddish in colour. 
fPhey start east of Somerton. near Glcnelg, extend through the 
Koo}'onga golf links, are well preserved near the Torrens, and 
continue up past Seaton, The Pinery, and Port Adelaide, and 
form the western part of Torrens Island. They are clearly marked 
on the accompanying map. and, as shown by Professor Cleland^ 
their flora is quite distinct from that of the surrounding plains, 
as well as from that of the present coastal sand-dunes. 
Cliffs of Softer Rocks. — The first series of limestones and 
mudstones occurs at Halletts Cove, wdiere they appear to have 
been let dow n b}- faulting. With these is preserved a small patch 
of very interesting glacial rocks of Permo-carboniferous age. 
These glacial' rocks overlie and protect a great sheet of ice-planed 
I'ock surface; the best known exposed area is that knowm as 
Tate’s Rock, commemorating the place where Professor Ral[>h 
Tate made some early investigations regarding this ancient glac- 
ial period. This area has also been much worked on by Professor 
Howchin and Sir Edgeworth David, and has been visited by prac- 
ticallv evcr\' geologist who has come to the state of South Aus- 
tralia. 
Phe '‘Amphitheatre’’ at Ilalletts Cove is a remarkable exam- 
ple of erosion bv running water In soft, level-bedded limestones 
and mudstones, lire sand-dunes and the limestone and mudstone 
cliffs at Port Xoarlunga have ail the characteristics of those al- 
ready described. Tlie same is true of the sand-dunes of Moana, 
Port Willunga and SelUcks Beach, and of the limestone cliffs of 
