199 



in sit//, then the questions arise, When did this transport 

 take place 1 and, Why is not a similar agency in operation 

 at the present time ? 



At the present time there are no permanent streams on 

 Yorke Peninsula and practically no land drainage reaches the 

 sea. Horse Gully is grass grown, and at its mouth the only 

 evidence of stream transportation is in the form of a narrow 

 band, about 2 feet in width, containing small stones of less 

 size than marbles, whilst the rest of the bottom is covered 

 with grass. On the testimony of the oldest residents, cover- 

 ing fifty years of experience, there has never been sufficient 

 water in the gully to transport the smallest stones within 

 their knowledge. The Archaeocyathinae pebbles on the 

 beach are usually from 6 to 9 inches in diameter, with larger 

 stones of the impure variety, which would require a con- 

 siderable body of water for transport. 



The possibility of the pebbles having been derived from 

 rocky reefs through wave action is at present incapable of 

 proof. The sea cliffs consist of clay of unknown thickness, 

 and no investigations for testing the presence of such reefs 

 have been carried out along the littoral and shallow margins. 

 The more plausible suggestion seems to be that of stream 

 erosion and delivery at some past time, and« the present rela- 

 tively dry condition of Horse Gully, and others of a like 

 kind in the neighbourhood, may arise from underground 

 channels and caves in the limestones by which the existing 

 drainage finds a passage downwards instead of to the sea. 



3. Dovilingville. At Thompson's Hut, Section 128 

 (Hundred of Cunningham) strong exposures of Cam- 

 brian limestone occur in the bottom and sides of a shallow 

 creek, close to the main road, near Dowlingville. The out- 

 crop measures 160 yards in length by 40 yards in width; 

 strike, north-north-west to south-south-east; dip, 25° 

 easterly. The stone is a dark, bluish-grey limestone, exactly 

 corresponding to the fossiliferous beds of Horse Gully, and 

 is sparingly fossiliferous ; the only other example than that 

 of Horse Gully of a fossiliferous Cambrian limestone within 

 the area under observation. Little time could be devoted to 

 fossil hunting, but several fragments of trilobites were 

 detected in the stone. The rise on the southern side of the 

 valley, under which the limestone passes, is thickly strewn 

 with travertine. 



LOWER LIMESTONE (dOLOMITIC). 



The lowest member of the Cambrian limestones in the 

 neighbourhood of Ardrossan is a finely granular, white or 

 yellowish dolomitic rock. Its position in the series is defined 



