
628 RECORDS OF THE S.A. MUSEUM 
PRESENT SHORELINE OF THE SOUTH EAST OF SOUTH AUSTRALIA. 
Study of the ‘Recent or ‘‘ Present’* coastal dunes at many places. between the 
Glenely and the Murray Rivers yields a wealth of data on the state of maturity 
of the ptegent shore and indications of the complex local histories of cutting and 
filling which haye culminated in the present shoreline, Ward (1941, p. 10) has 
indicated the difference in shore patterns between the Coorong dunes and those 
south of Cape Jaffa. 
Johnson (1919, 1938) and von Engeln (1942) have shown that on a shallow 
coast a drop in sea level brings into play a well-marked series of events and 
commences a eycle Of marine erosion whose normal sequences are well marked. 
As the sea falls the shoreline moves seaward and a foreland or strand plain 1s 
developed at land’s edge. Because of the shallow water on such a strand plain 
the larger erogiye waves will break a great distanec off-shore and as formation of 
detritus begins, a submarine bar will appear. At this stage a small notch will 
mavk the landward margin of the strand plain. Eventually the submarine bar 
will rise above sea level and become a permanent shore bar, comparable with the 
coastal dunes of the present Coorong, Detritus is added to this off-shore bar; it 
grows and may at first extend seaward for some distance, dependant on the 
initial slope of the emergent land surface. Between Kingston and White Hut the 
dunes are growing in this manner, Behind the bar forms a swamp lagoon, 
comparable with the Coorong Lagoon and with lakes such as Bonney, George, 
Eliza. These swamp lagoons will have varied physiographic and faunal histories 
depending on their access to rivers, their salinity and their possession or lack of 
outlet to the sea. Gradually they will fill with swamp deposits, as, for example, at 
Beyilaqua Ford and the Causeway. During the filling processes transverse bars 
may form in the lagoon and divide an originally continuous lagoon into several 
smaller ones, a8 at Lakes Eliza, St. Clair and Bonney, This stage of development 
is brought to a close by deepening of the foreshore by wave erosion, as at Cape 
Martin. The foreshore is then attacked and its deposits thrown further and 
further on to the shore, as on the Coorong near Barker Knoll and at Lake Bonusy 
where wind-blown dune sands transported from the coast are encroaching on the 
lagoon. In places the dunes may be breached, at first only temporarily, as perhaps 
indicated by an intercalated marine phase at Lake Bonney, and then permanently, 
as. at Beachport and Robe. Eventually the shore deposits may moye so far 
inJand as to overwhelm the swamp lands and lagoons behind the original bar. 
At this stage or before, the seaward margin of the sand-buried lagoonal deposits, 
projecting from beneath the mantle of dune deposits, may come under direct attack 
by the sea, as at the South Australian-Victorian border, and at Blackfellow Caves. 
With progressive erosion a final stage will appear in which the swamp lands are 
