CAMBRIAN AND PERMO-CARBONIFEROUS GLACIATION. 207 



(c) Many of the erratics are distinctly ice-marked under the 



forms — faceted, soled, striated, and polished. 



{d) The line-grained sandstones of the lower Finniss exhibit a 



peculiar grain in the stone, both macroscopically and 



microscopically. In place of regular bedding planes^ 



there are strong corrugations, as though the sediment 



had been subjected to a ploughing action at the time of 



its deposition, some of the sandstones are so markedly 



curved in the grain that they are rejected for building 



purposes. Even the fine-grained portions, in which no 



distortion can be recognised in the quarry, develop 



similar features under weathering. 



[e) Microscopically, the sandstones have a very distinctive 



character, quite unlike ordinary waterworn sand grains. 



The granular fragments are all intensely sharp, often 



mere splinters, and even the finest grains have the same 



features, corresponding to a "rock- flour." The greater 



induration of these glacial freestones has probably arisen 



from the interlocking, under conditions of pressure, of 



the angular fragments of which the rock is composed.^ 



Yankalilla, Normanville and Second Valley. — ^The great glacier 



which filled the Inman Valley, travelling westwards to unite with 



the still greater ice-sheet of the Valley of St. Vincent, passed over 



the Bald Hills and spread itself over the plains of Yankalilla, 



Torrens Vale, and the present coastal districts between Myponga and 



Cape Jervis. 



On the north side of Yankalilla glacial deposits are found in 

 most of the sheltered situations, as in the Carrickalunga Creek and 

 in the valleys intersecting the Archseocyathinas limestones. 



Going south, along the coast, the glacial beds can be seen on the 

 landward side of the Normanville Gorge, with a large granite 

 boulder on the saddle between the Great and Little Gorges, and 

 extensive washouts in glacial till in the paddocks. 



Interesting road cuttings in the till occur near the residence of 

 Mr. E. C. Kelly (Anacotilla), and at Poole's Flat, about one-and-a- 

 half mile further south, there is a remarkable display of very deep 

 washouts in the till, exposing numerous erratics, many of which are 

 strongly glaciated. These washouts have led during the past season 

 to a landslip of agricultural ground that covers an area of more 

 than three acres in extent. 



At Second Valley, from near the coast to the marble knob 

 near the hotel, the superficial beds consist of glacial drift exposed 

 in washouts. In the western angle of Section 1568, near the old 

 district road which runs parallel with the coast, are two large 

 boulders of granite, each 3 feet by 2^ feet, and a round boulder of 

 dolomitic limestone 2 feet in diameter. The drift passes over the 

 saddle into Poole's Flat, already described. 



1 For a more detailed description of these beds, with illustrations, see Howchin's paper (loc. cu. ante.) 



