} 
GLACIAL ACTION—SOUTH AUSTRALIA. 115 
The physical features of the country lying between Yankalilla 
and Cape Jervis can be best dealt with when the glacial evidences 
of this district are described. 
Glacial Features.—The Inman Valley. 
The Inman Valley holds the first position in the history of 
the discovery of proofs of former glaciation in Australia, and 
Mr. Alfred R. C. Selwyn, at that time Government Geologist 
of Victoria, had the honour of making this discovery. Whilst 
travelling through the Inman Valley in 1859, engaged on a 
cursory geological examination of the country under instructions 
from the South Australian Government, Mr. Selwyn was fortunate 
in observing a polished rock surface, which, to his practised eye, 
exhibited clear proofs of glacial action. In his official report he 
says: “At one point, in the bed of the Inman, I observed a 
smooth striated and grooved rock surface, presenting every indi- 
cation of glacial action. The bank of the creek showed a section 
of clay and coarse gravel, or drift, composed of fragments of all 
sizes, irregularly imbedded through the clay. The direction of 
the grooves and scratches is east and west, in parallel lines, or 
nearly at right angles to the strike of the rocks; and though 
they follow the course of the stream, I do not think that they 
could have been produced by the action of water, forcing pebbles 
and boulders detached from the drift, along the bed of the stream. 
This is the first und only instance of the kind I have met with 
in Australia, and it at once attracted my attention, strongly 
reminding me of the similar markings | had so frequently 
observed in the mountain valleys of North Wales.”* Whilst 
Selwyn made this striking discovery, he does not seem to have 
noted the cognate evidences of glaciation in the extensive deposits 
of drift, glaciated stones, and great erratics which form the chief 
geological features of the valley. 
In May, 1892, Mr. H. Y. L. Brown, Government Geologist, 
S.A., published an official “Geological Report upon a Shale 
Deposit in the Hundreds of Encounter Bay and Yankalilla,” in 
which he says: “This formation consists of a jointed shale, 
varying in colour from a bluish green to black, and interstratified 
with them there are undulatory beds of sandstone and quartzose 
sandstone, and occasionally limestone of irregular thickness. The 
upper portion of this shale, which in some places exhibits a 
concretionary structure, has become decomposed into clay, and 
contains water-worn pebbles and boulders of granite, quartzite, 
sandstone, ironstone, &e. Some of the boulders of granite are of 
great size, and in character resemble the granite of Victor 
Harbour. At one or two places on the Inman River there are 
* Geological Notes of a Journey in South Australia from Cape Jervis to Mount Serle, 
No. 20, p. 4. 
