294 PROF. T. W. EDGEWORTH DAVID ON [May 1 896}- 



II. Latest Observations by the Author. 



(a) Hallett's Cove. 



In December 1894 the author visited Hallett's Cove, near Adelaide, 

 in company with Prof. Ralph Tate and Mr. A. W. Howchin, with 

 the view of determining the question as to whether the glacia- 

 tion was post-Miocene or pre-Miocene. This question had been 

 discussed on the ground, during the meeting of the Australasian 

 Association for the Advancement of Science at Adelaide in 1893, by 

 Prof. Ralph Tate and a party of the members. Por the purpose of 

 finally settling the question, the Association placed the sum of <£20 

 at the disposal of the members of their Glacial Committee, to enable 

 them to cut a trench from the glaciated rock-pavement, across the 

 outcropping edges of the glacial beds, up to the base of the Miocene 

 limestone. Trenches were cut under the supervision of the above- 

 mentioned members of the Committee, and with the permission of 

 Mr. W. Reynell, and these excavations proved conclusively that the 

 glaciation was pre-Miocene. These results have already been 

 communicated by the Glacial Committee to the Australasian Asso- 

 ciation for the Advancement of Science. 1 Briefly summarized, the 

 Report is as follows : — 



The formations represented at Hallett's Cove are : — 



1. Pre-Cambrian rocks, consisting of hard, purplish-red clay- 



slates with greenish bands, grey quartzites, and thin bands 

 of siliceous limestone. The prevalent dip is "W". 10° to 20° N. 

 at from 40° to 78°. Wherever a fresh surface of these rocks 

 has been exposed by the denudation of the overlying glacial 

 beds, it is seen to be smooth and strongly glaciated, the strise 

 being sharply cut and as freshly preserved as though they 

 had resulted from recent glacial action. Their trend is 

 nearly north and south, and it is clear that the ice which 

 produced them came from the south. The glaciated surface 

 ascends to about 100 feet above sea-level, and descends to 

 probably a considerable depth below the sea-level. The 

 length of the glaciated surface preserved is about 1 mile, 

 and its width about J mile. 



2. Glacial Beds, consisting of reddish-brown clay-slates, sandy 



in places, and fairly well stratified, especially in their upper 

 portion. Downward they pass into sandy, greyish-brown 

 mudstones, containing well-striated boulders in abundance : 

 the latter occur only sparingly in the upper portion of the 

 deposit. Erratics, chiefly of porphyritic granite, and up to 8 

 tons in weight, are embedded in the strata at intervals. They 

 belong chiefly to a variety of granite occurring in place (dixit 

 R. Tate) at Port Victor, 35 miles south. The glacial beds are 

 from 23 to more than 100 feet thick, descend below sea-level, 

 and ascend to over 100 feet above the sea. No trace of any 



1 Rep. Austr. Assoc. Adv. Science, Brisbane, 1895. 



