﻿Vol. 64.] CAMBRIAN AGE IN SOUTH ATJSTEALIA. 235 



position they become obscured by the Tertiary sandstones of 

 McLaren Vale, and by a fault of some magnitude in which the 

 higher beds of the Cambrian series are brought into juxtaposition 

 with the lower beds at a divergent strike. 



North of the Onkaparinga, the glacial beds are occasionally seen 

 as iuliers of the Tertiary sandstones and clays, until the Eiver 

 Sturt is reached, 7 miles south of Adelaide. Here the beds cross 

 the stream obliquely, about 1 mile from the main South Road, and 

 occupy both sides of the valley for a distance of nearly 2 miles up 

 stream. The glacial beds in this locality are determined on their 

 northern side by a dip -fault, which cuts them off. 



From this point, northwards, the deep alluvial deposits of the 

 Adelaide Plains obscure the older series of rocks, along the strike, 

 for a distance of 50 miles. The glacial beds, with the associated 

 members of the Cambrian series, reappear on the west side of 

 Kapunda, and thence they occur (with slight interruptions from 

 faulting) in parallel belts as far as the northern extremities of the 

 Flinders Ranges. 



Many of the more prominent heights and ranges of hills owe 

 their elevation to the resistance which the glacial beds and the 

 underlying quartzites offer to the agents of waste, as compared with 

 the associated slates. Razorback and Mount Bryan, north of the 

 Burra, each about 3000 feet high, consist mainly of glacial till. 

 These beds also form the highest portions of the Petersburg 

 Ranges, as well as Stuart's Lookout, the Depot, Pekina Hill, 

 Mount Remarkable, the Oladdie Hills, and other considerable 

 elevations of the ' lower north ' districts. 



In the course of several visits to the Flinders Ranges the glacial 

 outcrops were followed, along their strike, for 60 miles, through 

 the country lying north-east of Leigh's Creek, and to the west and 

 north-west of Lake Frome as far as the Daly and Stanley Mines. 

 Mr. H. P. Woodward, in 1884 (when Assistant Government 

 Geologist), traced them still farther in the same direction, to Billv 

 Springs and Hamilton Creek, in the neighbourhood of Mount 

 Babbage (nearly at the north-eastern extremity of the Flinders 

 Ranges) ; and in these localities the included erratics were found 

 to be of great size. 



The till-beds, carrying glaciated erratics, occur also in the 

 Willouran Ranges, on the west side of Hergott, 440 miles north of 

 Adelaide, in 29° 50' lat. S. This is the northernmost point at 

 which the beds have been found in situ, but erratics, similar to 

 those which occur in the till-beds, are found scattered over the 

 plains, or forming part of rearranged material, in the Lake-Eyre 

 district, which may have been derived from the waste of the glacial 

 beds along the margin of the basin. 



The known extension of the beds, in a north-and-south direction, 

 from the Onkaparinga River to the Willouran Ranges, equals 

 460 miles. The greatest width is found along a line ranging fr ni 

 Port Augusta, at the head of Spencer's Gulf (where the beds crop out 

 in Mundallio Creek, on the western side of the Flinders Ranges) ; 



