from there the line of i unction between these fundamental 

 rocks and the Cambrian series runs southerly, a little to the 

 east of Goodwin Creek (Deep Creek), which latter flows in a 

 north and south direction, forming a junction with the River 

 Torrens just above the confluence of the Sixth Creek. The 

 Pre-Cambrian rocks cross the Torrens a little east of the outlet 

 of Goodwin Creek, in Sec. 5598 (Hd. of Onkaparinga), and, 

 after entering Sec. 335, recross the river to its northern banks, 

 in a north-easterly direction, about half a mile below the con- 

 fluence of Kangaroo Creek. 



The Pre-Cambrian country, in proximity to the river, is 

 extremely rough, thickly wooded, forming a high-level 

 plateau which, in physical features, is strongly differentiated 

 from the Cambrian rocks that fringe the area. It is here that 

 the river has cut the deepest and most impressive of its 

 gorges. The hard crystalline rock forms the chief barrier to 

 the river's action in establishing a uniform grade. On the 

 left bank the rocks rise to about 500 ft. above the river-bed, 

 whilst on the right they reach about twice that height, in 

 precipitous and dark-coloured frowning walls that cannot be 

 much less than 1,000 ft. in height. This very bold river 

 scarp is known locally as the "Devil's Staircase." 



The Pre-Cambrian rocks, as exposed in the river section, 

 consist of highly pegmatized schists, which pass into gneissic 

 rocks. The hardness of the rocks has limited the lateral action 

 of the river. The gorge is narrow, the sides and bottom are 

 deeply grooved and sculptured. Numerous pot-holes of all 

 sizes up to 6 ft. in diameter, and often very deep, cover the 

 uneven floor, and have even been excavated on the sides of 

 the canon. The severe corrasion by the stream has carved 

 the rocky floor into graceful curves, and has smoothed and 

 polished the surfaces. The finest part of this gorge is where 

 the river takes a sharp turn to the south, in Sec. 5495 (Hd. of 

 Yatala), from which point there are tumultuous rapids, ending 

 in a water-hole that carries the name of the ''Devil's Hole." 



CAMBRIAN. 



Between the Aldgate Pre-Cambrian inlier and that which 

 outcrops in the River Torrens, near Castambul, there is a 

 distance of eight miles. The intervening country consists of 

 the lower members of the Lower Cambrian series. In the 

 locality dealt with in this paper the Cambrians run out against 

 the older rocks and form a semi-circle of outcrops around the 

 southern end of the Pre-Cambrian massif, as explained below. 



