72 : THE HAWKESBURY SANDSTONE. 
‘becomes coated with a shining iridescent scum, which looks some 
what like oil, but is really a compound of peroxide of iron. The 
water as it oozes from the soil is colourless, but has an inky taste, _ 
from dissolved protoxide of iron. When exposed to the air, how- 
ever, this absorbs oxygen, and the peroxide is formed, which is — 
no longer soluble, but separates as a film on the surface of the 
water, and finally sinks to the bottom as a reddish ochre, or under 
somewhat different conditions becomes aggregated as a massive 
iron ore. <A process identical in kind with this has been # 
work at the earth’s surface, ever since there were decaying organic 
matters, dissolving the iron from the porous rocks, clays, and 
sands, and gathering it together in beds of iron ore or iron‘ 
It is not necessary that these rocks and soils should contain the 
iron in the state of protoxide, since these organic products ie 
are themselves dissolved in water) are able to remove a po ft 
the oxygen from the insoluble peroxide, and convert it oo | 
soluble protoxide of iron, being themselves in part oxy 
converted into carbonic acid in the process. 
hydrated peroxide of iron in the Hawkesbury rocks as — as 
preserved in the shales. Lenticular masses of coal and ae 
impressions are common. _In some of the concretions of —_ 
ferric oxides casts of the tougher fruits may still be found: | 
in a sandstone.on the Burnett River I have found a pt beautt 
fully preserved, and closely resembling some mesoz0le VF" 
" subject f At Dubbo 
Any one crossing the Blue 
capping of yellow pe on the sandstone. This yellow colour is du 
to iron, and represents the oxydization of the under 
materials, produced by water holding carbonic acid et on of the 
This carbonic acid is derived from the decaying vegeta” 
i 
[ 
grow on the surface, the yellow soil gives the reply. ne ‘that 
sents the surface vegetation of ages. We need not 
few or no fossil impressions remain of so abundant @¥ 
The oxide of iron consumes al jn an 
Mized origin of the strata.—We must not suppos? © ill 
origin of the strata. one explanation 
ee i : a ge on in one of the € ’ ~ a 
_ & description of what is at sens going Bs not heard of 
formations of Europe. few who ha’ 
