113 



treating of the Upper Palaeozoic rocks of the Mister colony, wo 

 find that geologist still further modernising the position of our 

 fundamental rocks. "Whether," he says, "the cupriferous 

 calcareous, and slaty strata of South Australia are, as I am 

 inclined to believe, members of the same group, is uncertain. 

 If so, they have not yet been recognised in Victoria." 

 Valuable, however, as Mr. Selwyn's geological observations are 

 in other respects to South Australian geology, yet his deduc- 

 tions now require modification in accordance with Mr. Tepper's 

 Peninsula discovery, that of Lower Silurian fossils in beds un- 

 conformably overlying the slaty cupriferous group of Selwyn. 

 But until more light is shed abroad on the subject we may 

 designate the group of rock constituting the Adelaide chain 

 and Munno Para hills by the somewhat ambiguous term " Pre- 

 Silurian." 



Geological Structure, Extent, and Surface Oharacteristicst — 

 A glance at the map and cross section will show the geological 

 structure of the Munno Para hills to consist chiefly of clay 

 slate, frequently intercalated w r ith bands of quartzites, and 

 less sparingly of marbles, and occasional veins of pure quartz, 

 principally in small nests and strings throughout the clay 

 slate. The length of the range may be estimated at from 24 

 to 26 miles, taking its rise on the south, a little to the north 

 of the northern boundary of the City of Adelaide, trending 

 northerly through Tatala, Munno Para — where it attains its 

 highest altitude — losing its characteristic outlines north of the 

 South Para River. The topography of the range is solely due 

 to denusive action, therefore the undulating and fertile table 

 lands of the Munno Para hills owe their outline and fertility 

 to the diversified character of the fundamental rocks out of 

 which they have been fashioned. 



Quartzites. 



Believing that the quartzite bands have acted a conspicuous 

 part in delineating the topography of Munno Para, I have 

 arranged them as follows, viz., west and east escarpment, and 

 middle or mill series. 



Using the cross sectional alignment as a base line, it will be 

 observed that only two of the separate bands of the western 

 escarpment series appear at the surface there. Proceeding 

 south, they are traceable through Sections 4161, 4148, 4147, 

 4159, and south-western portion of 4160. Prom that point, for 

 some distance south, both bands (especially the western) become 

 obscured by an easterly extension of the Drift formation in the 

 ancient gorge of Smith's Creek. The eastern one is well 

 exposed in a quarry in Section 4164. Strike of quartzite as 

 exposed in quarry 10° west of north ; dip 25° easterly ; esti- 



