105 
Notes on the occurrence of remarkable Boulders in 
the Hawkesbury Rocks. 
By C. 8S. Wirxryson, L.S., F.G.S, Government Geologist. 
Be Ge ee ee Sere | 
_ [Read before the Royal Society of N.S.W., 3 December, 1879.] 
Rey. W. B. Clarke the Hawkesbury Series, on account of the 
develo 
These strata consist principally of thick-bedded yellow sand- 
: * t . ed - 
_ glomerates. The true bedding is more or less horizontal—near 
Sydney Heads it has a slight westerly dip, but the minor stratifi- 
_ tation often exhibits diagonal or false bedding ; for instance, the 
ipping to the N.E. at an angle of 
e are much discoloured by oxide of iron, an 
by black oxide of manganese. Fragments of wood and thin 
_ Patches of coal occur in them. But it is more particularly 
: ss the shale-beds that I would now draw attention. These are 
-Yery irregular, both in thickness and extent: they may be 15 or 
20 feet thick in one place, and then, within the distance of a few 
nes and conglomerates. 
