307 



Pleistocene and Recent Beds in Section E. 



The Pleistocene and Recent beds in Section E maintain a close resemblance 

 to those already described that occur to the northwards. The form in which 

 the upper argillaceous beds retreat from the edge of the harder vmder-cliff is 

 well seen when Blanche Point is viewed from a short distance, or, when standing 

 on the midshelf formed by such retreat, as shown in pi. xxii., fig. 2. 



The outlet to Aldinga Creek (at Port Willunga) possesses some features 

 of geological interest. The creek has cut its way down to base level. Where 

 it makes its exit to the beach there are remains of an ancient carbonaceous mud 

 deposit that is sufficiently indurated to withstand the action of the waves for 

 some time. It is best seen on the northern side, as the southern banks are 

 obscured by drift sand. The present stream has worn its way down through 

 the old fluviatile deposit to a depth of about 8 feet without exposing its base. 

 The adjoining cliff, facing the sea, supplies a section of the bed to this extent 

 and shows that the carbonaceous mud deposit occupies the position of a wedge 

 that divides the older (mottled) clays from the newer reddish clays, and thins 

 out to nothing between these two formations. The indurated mud contains 

 many plant impressions, but these are too fragmentary and decayed for deter- 

 mination. In one place numerous shells of the gasteropod, Coxiella badgerensis, 

 were seen grouped together on one of the layers. This carbonaceous bed gives 

 evidence of the existence, at a former time, of a sluggish pool of fresh or brackish 

 water that flowed at a higher level than it does to-day, and probably met the sea 

 at a point further to the westward than it does at present. 



SUB-SECTION R 

 FROM A LITTLE SOUTH OF SNAPPER POINT TO SELLICK'S HILL 



BEACH ROAD (3i MILES). 



There are few physical features that distinguish this portion of the coast. 

 About a mile to the southward of Snapper Point the sea-cliffs disappear and are 

 replaced by low sand dunes which mark the northern side of the alluvial 

 valley, three miles in width, which represents the ancient river flats of the Onka- 

 paringa before its diversion 12 miles to the northward. The country between 

 Aldinga and Sellick's Hill, by road, is quite flat. On the Sellick's Hill side of 

 the valley a number of weak springs make a seepage from the hill sides. This, 

 together with a small amount of drainage derived from the local rainfall, finds 

 its way to the coast, but being dammed back by the sand dunes, forms a small 

 brackish lagoon (the "Salt Lake") which, in summer, usually evaporates, leaving 

 a saline incrustation on the surface. This is all that is left of what was, in the 

 near past, the outlet of one of the more important rivers of southern Australia. 



Shortly after passing the lagoon, going southward, the clay cliffs begin to 

 show again with a gradual increase in height. A serious washout has developed 

 in these beds at the lower end of the district road that leads from Sellick's 

 Hill to the beach. It is said to have been started by an adjacent landowner 

 having turned the drainage from his field into the road. The washout in its 

 lower reaches is divided into several branches which in the aggregate cover 

 and has rendered impassable about two acres of ground (in 1911), some parts 

 of the canyon reaching a depth of about 25 feet. 



SUB-SECTION G. 



FROM SELLICK'S HILL BEACH ROAD TO THE END OF THE 



FOSSILIFEROUS TERTIARY BEDS (3 MILES). 



The clay cliffs, which at the beach road have a height of about 30 feet, 

 gradually rise to the southward until they reach a maximum height of about 



