Harrison— On the Geology of Hobart Town. 493 
Churech—the claystone appears as a surface rock; the oval patch 
crowning Knocklofty is a compact greenstone, resembling that of 
Mount Wellington. 
It is worthy of remark, that nearly all the sand and claystones 
have a dip in the direction of Mount Wellington. This peculiarity 
of dip is not confined to Hobart Town alone, but seems to be general 
over the whole adjacent district, the only exception being upon the 
immediate sides of the mountain, and here the dip is directly oppo- 
site to that prevailing elsewhere. 
By the accompanying section (fig.2) it will be seen that, ex- 
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FAULTS. 
Fic. 2.—IDEAL SECTION OF HOBART FROM MOUNT WELLINGTON TO DERWENT RIVER. 
a. Basalt and Greenstone. 6. Limestone. c. Claystone. 
d. Sandstone. e. Coal-beds. 
> Indicates the spot where the femur of Labyrinthodon was discovered. 
eluding Mount Wellington and the basalts, the arrangement of the 
sandstones somewhat resembles a series of ratchet teeth, rising one 
above the other from the Derwent towards the south-west. As a 
very homely illustration, we may suppose a set of wooden cubes to 
be Jaid out upon a yielding foundation, say a sofa cushion, so that 
the surface of the whole represents a perfectly level superficies. 
Some disturbing force having changed the horizontal plane of 
each cube into a gently sloping incline, at every joint a diminutive 
escarpment was formed. If we now imagine that some molten sub- 
stance, such as wax, has been forced from below through the various 
interstices, so that the overflow partially fills up the miniature val- 
leys, we shall have a model representation of Hobart Town, with its 
sandstones, dislocations, and eruptive rocks. 
It will probably be asked why the dip of the various beds remains 
so constantly the same, and towards instead cf from an evidently 
upheaved rock? Perhaps the local dip in the opposite direction, 
mentioned as occurring on the sides of Mount Wellington, may, in 
some measure, explain the difficulty. 
If avast level plateau, such as once existed hereabouts, should 
ever become broken up by the protrusion of a ‘massif’ like the 
Mount Wellington range, it is not unreasonable to suppose that 
many fractures would take place at a distance from, and perhaps 
parallel éo, the intrusive mass. In addition to this simple fracture of 
