As one approaches this reserve from the plains, the bold 
mass of Black Hill is seen to the north, typical of the scenery 
and vegetation of the quartzite rocks. The hills at the entrance 
to Morialta are more rounded and grassy, quite different in 
character from those of Black Hill ; this is because they are 
formed of the more easily-eroded slates and phyllites. In the 
low cutting near the tram terminus, and in the higher roadside 
sections seen on the way to the kiosk, these rocks show many 
interesting features. Some of the slates are very calcareous, 
almost limestones. Here they are nearly level-bedded, very well 
jointed, bluish to cream in colour, with ochreous stains. There 
is a fairly strong development of horizontal quartz veins, accom- 
panied by green, glistening chlorite. Here and there one may 
see veins of calcite with beautiful rhombs. Occasionally, the 
fern-like markings of dendritic manganese oxide may be seen 
along the joint planes. In these cuttings, also, narrow crush 
zones mark the positions of some of the smaller faults that 
divide the mountains from the plains, while in most of the 
roadside cuttings there is a fine variety of hill-slip material 
(talus, scree) consisting of all sizes of angular boulders inter- 
bedded with soil. 
As we pass up the gorge towards the waterfall, the beds 
tend to take on a more and more steep easterly dip, until nearer 
the waterfall they become horizontal once more. The little 
stream which at present flows in this gorge is now called Fourth 
Creek, but originally was called Anstey Rivulet on the plains 
and Sinclairs Gully in the hills. The most interesting fact in 
the physiographic story of the gorge is that this small stream, 
working through a vast period of time, has carved out the whole 
of the valley and transported the materials westward to help to 
form the Adelaide Plains. 
The waterfalls, three in number, which now form steps up 
the valley of this stream, were once on the edge of the scarp 
and have slowly retreated up-stream by a process of erosion, 
just as they are doing to-day. It is a slow process, and it is a 
fine exercise for the imagination to try to picture how it has 
occurred. 
Just before coming to the kiosk (car park) the hill on the 
south, Hogans Hill (nine hundred feet), may be noted — more 
particularly for its smooth slopes and for the remarkable 
regeneration of sheoaks and golden wattles that has recently 
taken place there. Behind the kiosk a steep gully descends from 
the Norton’s Summit road. This feature, called Reade Gully, 
is the gateway to many interesting rambles along the pathways 
originally designed by the late Charles Reade. On the right 
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