I I 2 
T. G. B. Osborn. 
Creek. This is one of several arms of the sea which lie ten miles 
north-east of Adelaide and run between mud flats and mangrove 
swamps. Much of the area that is now land in this region has 
been submerged in recent times as is indicated by such names as 
Dry Creek. 1 
The Mount Lofty range consists of a synclinal fold involving 
rocks of the Cambrian age. The main axis is composed of basal 
quartzites which have been worn away in places exposing the older 
grits. The foothills consist for the greater part of the overlying 
slates. Much faulting has resulted in sharp junctions between 
slates and quartzite which are noticeable by their different floras. 
Vegetation. 
But little remains to show what was the original vegetation of 
the plains on which Adelaide stands. The evidence is that they 
were well wooded with various species of Eucalyptus ( E . rostrata 
by the water courses, E. viminalis, and nearing the hills E. odorata 
and E. leucoxylon). This is a marked contrast to the Northern 
portion of the coast plain which was, and still is, almost destitute 
of trees. 
About the coast and around Dry Creek area as well as on 
certain slopes of the lower foothills were probably many native 
pines (Callitris propinqua), but these are rapidly being exterminated. 
Amongst the introduced trees the Moreton Bay Fig ( Ficus macro- 
phylla), pepper trees ( Schinus molle), Pinus Halepensis and P. insignis 
are the most common. Vines, peaches and apricots thrive on the 
plains, but apples and pears are better grown in the hills. There 
are extensive orangeries along the Torrens and up the creeks into 
the foothills, while on the lower slopes are some famous vineyards 
and olive yards. The paddocks into which the plain is divided are 
used for wheat (grown in the winter months) and for pasture. The 
vegetation of the latter is largely composed of alien plants which 
will be referred to later. 
The plains are divided from the sea by a coastal strip. To the 
north-east lies the Port Adelaide Creek, and numerous other arms 
of the sea, intersecting low sandy flats. For the greater part of 
the year they receive little or no fresh water from the rivers drain¬ 
ing into them. The muddy banks of the channels are occupied by 
a thick growth of Avicennia officinalis reaching to a height of 12 to 
15 feet (PI. I, Fig. 1). The area immediately behind the mangrove 
1 Howchin, W. Trans. Roy. Soc. S. Aus., Vol. 30, 1906, p. 227 ; Vol. 36, 
1912, p. 34. 
