In the same bed are found nodules of barytes, with a 
radiating, concretionary structure. They are more or less 
spheroidal in shape, being fiat or concavely indented in the 
plane of the longer axis. Others are flatter, broadly dis- 
coidal. Their dimensions vary considerably, the largest 
being about four inches in diameter. The smaller forms have 
a tendency to slit horizontally in two.* 
A more argillaceous variety of desert sandstone, spangled 
with tiny flakes of mica, was observed south of Stuart's Creek 
Cattle Station. This outcrop weathers more like a shale than 
the sandstone generally. 
Fossilised wood was found in the desert sandstone at a 
few localities, notabl}'^ west of William Creek, in the neigh- 
bourhood of Beltabeltana Waterhole, where it is plentiful. 
Other fossils were not observed in this formation. 
The most picturesque and rugged range of disconnected 
masses of the desert sandstone formation came under notice 
in the locality known as the Serrated Range. This range is 
composed of peaks, bluffs, pillars, and tables, often of a very 
quaint appearance, and tinted in various shades of colour. 
The formation may with justice be called the Mauvaises Terres 
of Australia, as have been termed the Cretaceous desert for- 
mations of North America. 
Owing to the porcelainised, brittle character of the rock, 
particularly of the overlying hard band, it gives way readily 
and suddenly when subjected to irregular strain. It is on 
this account that the sandstone, wlierever met with, has been 
more or less broken up into fragments, often terminated by 
conchoidal faces ; the phenomenon being the result of subjec- 
tion to extremes of temperature within a short period of time 
(insolation). These fragments are subsequently scattered over 
the plains between the table-hills by the floods which occur 
at rare intervals, and are known as gibbers (less 
frequently shingle or gravel). The gibbers form 
* I have recently had opportunity of seeing identical concre- 
tions in the Sydney University Museum, which were collected by 
Mr. E. F. Pittman from the opnl-bearing strata at AVhite Cliffs. 
Through the courtesy of the Mines Department of New South 
Wales I have been permitted to annex the following analysis by 
Mr. J. C. H. Mingaye : — 
Analysis of a Nodule op Barytes obtained from Opal-bearing 
Strata at White Cliffs. 
04-1666 
Barium sulphate ... ... ... ... 95-35 
Ferric oxide and alumina ... ... ... -50 
Silica 2-60 
Water -72 
Lime, magnesia, and undetermined ... -83 
100-00 
