On some Tertiary Deposits in South Australia. 77 
of calcified stems of trees, standing in the position of their growth, 
in the sand-dunes of the Gulf of St. Vincent, near Adelaide. 
4, “On some Tertiary deposits in South Australia.” By the Rev. 
Julian Edmund Woods. Communicated by the President. 
The author, in the first place, described the geographical features 
of that part of the colony of South Australia to which his observa- 
tions refer. It lies between the River Murray on the west, and the 
colony of Victoria on the east ; and includes an area 156 miles long, 
N. and S., and 70 broad from E. to W. Some trap-dykes and four 
volcanic hills are almost the only interruptions to the horizontality 
of these plains, which rise gradually from the sea, and are occupied 
by the Tertiary beds to be noticed; they extend into Victoria for 
some seventy miles, as far as Port Fairy. 
In some places on the plains a white compact unfossiliferous lime- 
stone lies under the surface-soil; and is sometimes 30 feet thick. 
Under this is a fossiliferous limestone. The passage between the 
two is gradual. This latter rock is made up of Bryozoa—perfect and 
in fragments—with some Pectens, Terebratule, Echinoderms, &c. 
Sometimes this rock appears like friable chalk, without distinct 
fossils. A large natural pit, originating from the infalling of a cave, 
occurs near the extinct voleano Mount Gambier, and is 90 feet 
deep—showing a considerable thickness of this Bryozoan deposit in 
several beds of 14 ft., 10 ft., 12 ft. thickness. Similar pits show 
the deposit in the same way at the Mosquito Plains, 70 miles north. 
Regular layers of flints, usually black, rarely white, occur in these 
beds, from 14 to 20 feet apart. These, with its colour, and with 
the superficial sand-pipes, perforating the rock to a great depth, give 
it a great resemblance to chalk. 
The whole district is honeycombed with caves—always, however, 
in the higher grounds in the undulations of the plains. 
One of the caves, in a ridge on the northern side of the Mosquito 
Plains, is 200 feet long, is divided into three great halls, and has 
extensive side-chambers. The caves have a north and south direc- 
tion, like that of the ridge. ‘The large cave has a great stalactite 
in it; and many bones of Marsupialia are heaped up against this 
on the side facing the entrance; possibly they may have been 
washed up against this barrier by an inflowing stream. The dried 
corpse of a native lies in this cave. It has been partially entangled 
in the stalactite ; but this man was known to have crept into the 
cave when he had been wounded, some fourteen years ago. Many 
of the caves have great pits for their external apertures, and contain 
much water. 
Some shallow caves contain bones of existing Marsupialia, which 
have evidently been the relics of animals that fell into the grass- 
hidden aperture at top. 
The caves appear in many cases to be connected with a subterra- 
nean system of drainage; currents and periodical oscillations being 
occasionally observed in the waters contained in them. There is but 
little superficial drainage. One overflowing swamp was found by 
