92 THE HAWKESBURY SANDSTONE. 
to take a circuitous route along the flanks of the sand ridges 
The sand is of a red colour, and is evidently derived from the 
ferruginous quartzite rocks (probably Cretaceous), which, ina * 
fragmentary state, crop out at intervals, and form the s i 
may mention another instance, though but a small one, with — 
which you all are familiar. The valley lying between Sydney and 
Botany Bay is partly filled with blown sand deposits, while her 
and there occur small lagoons, in which carbonaceous sediment is 
accumulating. To a certain extent this illustration may serve ® 
show sandstones and irregular shale beds in process of formation; 
but only in a small degree will they resemble the sam : 
dulating and hilly surface of these blown sand areas. Now, if 
you look at the beautiful sections exposed in the cliffs along the 
Bondi coast, or in the smaller cliffs fringing the harbour, or 0" 
still, in those magnificent precipices in the Blue Mountains ve 
ost prominent feature that you will notice is the horizon — 
bury formation, and this alone is evidence of the beds having é 
deposited under water. But in wind-blown formations such sia 
their origin to dust-storms; for, in their laminated prs 
they exactly resemble the aqueous rocks of the Coal Meast" eS 
other formations. Then, again, there are the bonacee sf 
beli be of ats 
f 
the fine earthy matter which could not settle in the carrey s 
drifted the sand along, now settled down in the she@l,  tyg 
place is very clear, I will adduce further proof of yar 
i ying t Bok : 
