■S.A. X.vr., VOL. XIV. 
Avgust 31st. 1933. 
By C. Fenner, D.Sc. 
133. 
y\Idinga and SelHcks Beach. There are in addition curious dif- 
ferences from place to place, which are not here mentioned in 
detail but are left for the reader to inveslgate. The limestone 
■cliffs contain a wealth of fossils, and have been a happy hunting 
ground for collectors for the past seventy years. 
Cliffs of Harder Rocks. — The hard cliff buttresses, where 
the ancient rocks resist the attacks of the sea, are characteristic 
'of the area from Marino to Halletts Cove, from the Field River 
to Morphettvale Creek, from Pedlers Creek for two miles south, 
and from Sellicks Hill southward. 
These rocks consist mainly of purple to gray quartzites; 
usually these have an almost vertical dip, but there are places 
where there is evidence of the great earth forces that have crum- 
pled them into complex folds. In other places, as at the base 
of Sellicks Hill, thick beds of limestone are found. Sir lulge- 
worth David has published accounts of some very primitive fos- 
sils from these rocks at Reynella, while in the Sellicks Hill lime- 
stones, near the top of the ridge, specimens of ancient “sponge- 
•corals,’’ the Archaeocyathinae (ancient cups) may be found. 
Drainage and Soils. — Along the coast all varieties of er- 
osion may be studied: marine, aeolian, pluvial and glacial. 
Similarh* there arc examples of the most varied types of drain- 
.age, from sodden mud-flats, through porous limestones and dunes, 
to high and well-drained hillslopes. All these points are of im- 
portance to the field naturalist, for your true naturalist is not 
a mere collector, nor a mere observer; he must strive to seek 
relations between things, and to discover causes. A plant’s chief 
interest may lie, not so much in itself, as in its position on a 
■slope, the accompanying plants, the underlying rocks and soils, 
the type of drainage and erosion. 
The whole of the area, apart from cliff faces, is covered with 
,a widespread mantle of rock waste. Upon this mantle the effects 
'of wind, rain, and sun for some tens of thousands of years has 
produced the features we call soils. There is quite a variety 
of soil types within this area, with their different colours and 
profiles, depending in part on the rock-type below, but much 
more upon the slope and drainage of the locality. Each soil 
type has its appropriate plant suite; and each native plant com- 
munity has certain introduced plants that most commonly dis- 
place them or take possession when the native growth is destroy- 
'cd. Nor should we forget the more elusive native animals, in- 
cluding the birds, the shells, and the beach life, that also take 
their selected and appropriate place in the scheme of^ things. 
Lucky indeed are the field naturalists who have at their doors 
..an area of such rich and varied interest. 
