Sixty-eight 
THE SOUTH AUSTRALIAN NATURALIST 
June, 1953 
red sandstone with a horizontal 
cap of hard igneous rock 
(Porphyry). It is this caprock 
(varying in thickness up to about 
30 ft.), which gives the range its 
typical “Tabletop” appearance 
and is preventing the erosion of 
the underlying softer rock. Were 
it not for this layer of rock the 
Gawler Range would long ago 
have disappeared. The tops of 
these hills, which are compara- 
tively flat, vary in width up to 
150 yards, carry very little soil, 
and much to our surprise the only 
trees of consequence that we saw 
was Melaleuca pubescens , which 
we had previously found growing 
in the salt creek on the plain. 
On looking back over the route 
traversed in reaching the hills we 
were struck by the clearly defined 
dividing line between the Myall 
and Black Oak trees. It was noted 
that the actual point of division 
was a small watercourse, the 
Myalls growing in the strongly 
alkaline soils to the west of the 
creek and the Black Oaks in the 
more acid soils formed by the 
weathering of the rocks from the 
hills. 
And so we made our way back 
to the car, not much richer in 
botanical specimens. Still we had 
seen much to interest us and to 
give us thought and to speculate 
upon for we had satisfied our- 
selves that the two plant families 
first mentioned provide at least 
90 per cent, of the plants of this 
area. 
OLIVE TREE ON ST. PETER 
In “The Advertiser” of 15th 
March, 1951, is a photograph of a 
small tree, said to be eight or ten 
feet high, which could be seen 
waving over the stone rampart at 
the pediment of the spire on the 
south-west tower (the bell-tower). 
The accompanying legend stated 
that there “a windblown seed came 
to rest and sprouted.” As the 
shrub shown in the photograph 
looked to me rather like an olive, 
1 made an inspection of it with 
field-glasses a few days later. 
It was growing on the northern 
aspect of the tower and was as ex- 
'S CATHEDRAL: ADELAIDE 
pected an olive. Several domestic 
pigeons were on the parapet be- 
side it and there was considerable 
fouling with their excreta. I do 
not know whether domestic 
pigeons ever eat olives with stones. 
I think it almost certain that 
starlings were responsible for the 
seeding. 
At a similar height on the 
South-East tower a sowthistle 
could be seen, and this was un- 
questionably from wind-blown 
seed. 
J. B. Cleland. 
