A492 Harrison— On the Geology of Hobart Town. 
racter of the rocks varies considerably. The land, therefore, may 
be presumed to have once presented a very different line of contour 
to what it does at the present day. 
In bygone geologic ages, Tasmania must have been represented 
by at least five rocky islets. Then the intervening sea-bottom 
became raised, and the area appeared as one continuous mass of 
land, deeply indented, however, by two gulfs, which being in time 
filled with aqueous deposits, now constitute the respective coal- 
basins of Campbell and Hobart Towns. It is to the geology of the 
latter basin that the following notes bear reference. 
Following the road from Hobart Town to New Norfolk (a town- 
ship situate on the Derwent, and about twenty miles from the metro- 
polis), there are met with a succession of Carboniferous shales and 
sandstones, cut by numerous dykes and masses of eruptive green- 
stone and black basalt, or covered over by gravel and other aqueous 
deposits, until near Bridgewater (ten miles from Hobart Town), 
where there is exposed a dense claystone, which is in turn succeeded 
by thick beds of highly fossiliferous limestone. ‘The latter, after 
extending for several miles, and presenting a gradually rising series, 
dip in quite a contrary direction, so that at New Norfolk the clay- 
stone of Bridgewater is again met with, and then, still further on, 
towards Hamilton, are beds of sandstone, shale, and coal, appearing 
in the reverse order of the succession passed over in journeying 
from Hobart Town to Bridgewater. It would seem, therefore, that 
an anticlinal axis exists near the latter place (see fig. 1). 
N. Norfolk. 
SE. NW. 
-.. Knocklofty. 
----- Hamilton. 
-----~- Mt. Nelson 
Mt. 
-- Wellington 
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a Bridgewater. 
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pales 
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Fig. 1.—SANDY BAY vid HOBART TO NEw NORFOLK.* 
(The whole of this section is much cut up and disturbed by dykes of basalt, &c., which 
are not shown.) 
Along nearly all the other routes pretty much the same series of 
rocks is met with, only that the limestone seldom appears at the 
surface : in the lines leading up Mount Wellington, however, the 
last-named rock is met with at barely a mile from the boundary 
of Hobart Town. This is simply the result of great disturbance and 
denudation having taken place thereabout. 
The area of Hobart Town is traversed by a series of broad stripes 
alternately of sandstone and basalt. In one locality—near Trinity 
* For an explanation of the letters, see fig. 2. 
