84 THE HAWKESBURY SANDSTONE. 
- Coneretions.—Concretions or fragments of rock broken small — 
and the edges abraded present pebbles of every variety of colour 
and apparent consistency. ‘This can be easily seen by the examina — 
tion of pebbles at the bottom of any stream. The river Medway — 
in Central Queensland flows through a sandstone in every respett 
like the Hawkesbury sandstone, though it may be older, as tis 
full of impressions of Lepidodendron nothum and other plants — 
The pebbles at the bottom of the stream are of every colour, and 
differ much in mineral character. Some have come froma 
brook. The conclusion I draw from this fact is that it is not 
tegrated by simple aerial weathering. This is no forced hypothesis 
38, 
Stony Deserts.—In Central Australia, or rather south of the 
centre, between the 28th and 29th parallels of latitude, the -_ 
is distinguished by two features which entitle it to the names aor 
the Stony and the Sandy Desert. The latter is a series 0 red me 
ridges, whose glaring colour and whose aridity render then 0 
striking objects. 20 or 30 miles of such sand is a on Oe 
theories have been s 
‘ - . p posed ay . ft Hy 
“ favourite of which is, that they are the remains feb 
long-continued current of water running through the My owt : 
opinion is that these stones are the remains of a highly f 
* Discovery and Exploration of Australia, vol. 2 P10 
