in New Countries. 
9 
pared together, we are obliged to fall back upon the 
evidence afforded by organic remains in order to get at 
least a common base from which to commence. Even 
here, however, when once such base is even approxi¬ 
mately ascertained, sections, and the working out the 
solid geometry of the country, come into play both to aid 
and to correct the results derived from the examination of 
organic remains. 
I will conclude these few hastily written observations 
with a brief mention of my impressions of the geology of 
the neighbourhoods of Hobart Town and Sydney. The 
rocks of the south-eastern portion of Tasmania, from 
Ross to Port Arthur, seem to be composed principally 
of one large aqueous formation, and a great quantity 
of igneous rocks. The Schouten Islands are com¬ 
posed of granite ; but on the main land the ranges or 
“tiers” of hills, as they are appropriately called, are 
formed principally of greenstone, commonly known in 
the country under the name of ironstone. These tiers 
have very irregular outlines and directions ; they fre¬ 
quently inosculate, and enclose plains or wide valleys, 
such as Bagdad Plains, Green Ponds, Brushy Plains, 
and others. The aqueous formation consists of a great 
mass of sandstone, containing beds of shale, limestone, 
and coal. The sandstone varies in different localities, 
from a smooth compact quartz rock to a grey fine¬ 
grained gritstone, a yellow or grey conglomerate, fre¬ 
quently like greywacke, or a soft crumbling sand. It 
frequently contains beds of excellent white freestone. It 
is usually found in nearly a horizontal position, but is 
continually interrupted by masses of greenstone or basalt. 
Casts and impressions of shells are found in the sand¬ 
stone, but they are, together with corals, most abundant 
in the limestones. In the shales near the coal are the 
impressions of plants, I have not been able to detect 
