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I. SKETCH OF THE GEOLOGICAL FEATURES 



L Pleistocene Deposits. 



■ Southern Yorke-Peninsula may be described as a saucer, the lip 

 being constituted of blo^vn-sands, loose atop but more or less 

 consolidated below, generally ha^dng a breadth of a half to two 

 miles, and attaining elevations up to 200 feet or so. Inside the 

 lip are extensive areas of flat marsh-lands or shallow salt-pans, 

 constituted of sands with much shell-debris, loose or variously 

 compacted ; in the majority of cases the top layer forms a hard 

 pavement-like surface of a few inches thick ; less commonly these 

 low areas are levelled up with a natural whiting, of good quality, 

 for a depth of at least three or four feet. 



The low-levels are varied by ridges, which seem to owe their 

 origin to wave-action, or they may be of the nature of sand-bars. 



The fossils in the consolidated calciferous sandstone through- 

 out the whole area belong to existing species. 



The whiting has been examined for microzoa by Mr. "W. 

 Howchin, F.G.S., but he fails to find any trace of them. I suggest 

 that the material has originated by the accumulation of exfoliated 

 shell-substance, washed out of the incoherent shell-banks. 



The whole of Southern Yorke-Peninsula is constituted of these 

 Pleistocene deposits, except such limited areas as are now to be 

 mentioned. 



IL Eocene Limestones. 



The sea-clifFs of Point Turton, which are about 40 feet high, 

 are composed of a red polyzoal limestone, sometimes very dense 

 and marble-like, also exhibiting most pronounced current-bedding. 

 Point Turton is the northern termination of a ridge, which 

 has a general N.N.W. and S.S.E. trend and attains an eleva- 

 tion of 200 feet or so at Warooka ; by this physical feature, 

 it may be inferred that this limestone forms the western boundary 

 of the Great Salt-Marsh for a little more than half its leng-th. 

 From the few fossils observed, the Warooka ridge is an outlier 

 of the Eocene limestones which form the sea-cliffs on the east 

 coast of Yorke-Peninsula, extending from near Black Point, by 

 Surveyor's Point (Port Yincent), Stansbury, Wool Bay to Point 

 De Mole at Edithburg. 



III. Arch^an Rocks. 



At Point Souttar, and along the coast for a few miles to the 

 westward, mica-schists, occasionally gneissoid, appear in low reefs 

 on the shore-line. Similarly at Corney Point, the Pleistocene 

 cliffs are based on mica-schist, intersected by narrow granite 

 veins, in which the felspar largely predominates. These condi- 

 tions are repeated at Daly Head. At an unnamed point, S.W. 



