12 



a leading geological feature in the Petersburg Ranges, along 

 which I followed their outcrop for a distance of sixteen miles. 

 In some places fine mural exposures of the ''till" were met 

 with, and large boulders of quartzite, granite and other kinds 

 of igneous rocks, weathered out from the "till," lie strewn 

 upon the surface. 



Jamestown is situated about twenty-one miles to the south- 

 west of Petersburg. In the Belalie Creek, about one mile 

 east of the town, the junction of the "till" beds with the 

 overlying "ribbon," or banded, shales of the Tapley's Hill for- 

 mation is well seen. The outcrop can be traced across the 

 railway line, and occupies the rises on its northern side. On 

 the cultivated land the farmers of the neighborhood have 

 been at much trouble to clear the ground of the erratics, which 

 are in great numbers, and in places tlie task has been too 

 much to attempt, so that the stony ground is left in a state of 

 nature. In one spot, near the boundaries of Mooreland's 

 Parm, a fine field of erratics can be seen strewing the ground 

 of all sizes up to nine feet in diameter. 



The northern exposures of the "till" beds differ in one im- 

 portant particular from those of the Sturt Valley. In the 

 latter locality but few boulders are ,found lying on the sur- 

 face of the outcrops , whilst in the north such free erratics 

 are extremely plentiful, probably arising from the more rapid 

 weathering of the beds. This extensive weathering is a 

 feature of great importance, as it permitted a freer examina- 

 tion of the erratics than is possible in the formation near 

 Adelaide. 



The crowning result of these observations in the northern 

 districts, and one that has placed the question of the glacial 

 origin of the beds beyond all doubt, was the discovery of 

 glaciated stones of the most distinct and characteristic tjrpes. 

 A large limestone boulder and several quartzites have been 

 obtained which show glacial facets as well as groves and 

 striae. 



I have ventured to refer the glacial beds described in this 

 preliminary note to Cambrian age. At present this is only 

 a matter of inference, but the weight of evidence seems to 

 point in that direction. 



I do not think they can be regarded as newer than the 

 Cambrian, as they underlie a thick series of shales and lime- 

 stones, so little altered that, had the latter been of more 

 recent date than the Cambrian, they might reasonably have 

 been expected to carry some palaeontological evidence of their 

 age ; but, with the exception of Radiolaria, they have given 

 negative results after repeated searchings. Further, the "till" 



