358 
throughout the limits of the basin, whose limits have been 
thus roughly sketched. 
MESOZOIC ROCKS. 
The Mesozoic Period has been aptly termed the “ Age of 
Cycads,” because of the abundance of plants of this type «f 
the Mesozoic age. With the exception of the Mersey Coal 
Measures, it has now generally been admitted that the 
various coal seams, and associated shales, and variegated 
sandstones overlying the Upper Marine Beds of Carboniferous 
age in Tasmania, belonging to the Mesozoic Period. These 
rocks are mainly distributed throughout the Midland and 
South-eastern parts of the island, although the existence of 
coal at a great height, near the Eldon Range, on Coal Hill, 
with remains of the variegated sandstones flanking all the 
great western tiers, associated with the Carboniferous rocks, 
indicate that the numbers of the Mesozoic rocks were pro- 
bably at one time conterminous with those of the Carbon- 
iferous rocks, 
With the exception already named, therefore, the dark- 
grey shading of the sketch map, and perhaps a considerable 
portion concealed under the Launceston Tertiary’s Basin 
colored yellow, make up the whole area within which the 
several basins of the Mesozoic rocks occur. 
In a general way the existing evidence tends to show thaé, 
as the floor of the ancient Upper Paleozoic sea was gradually 
being elevated above its waters at the close of the 
Carboniferous period, seolian, atmospheric, and organic 
agencies immediately began to operate upon it in carving out 
valleys and river-channels, and in filling its many cup- 
shaped basins and irregular hollows with lakes and sediments. 
It is mainly from such waste, and by such agencies, modified 
by igneous intrusions, that the sediments and materials of 
the lower rocks of the Mesozoic period were deposited in 
Tasmania. 
So far as my observations go, there is every reason 
to believe that the larger part of its surface, including 
that portion of the Upper Paleeozoic rock underlying the Ter- 
tiary lake deposits (coloured yellow), has been permanently 
elevated above sea level since the close of the Upper Paleozoic 
age—that is, since the Upper Marine Beds, with their charac- 
teristic spirifers, fenestelle, stenopore, etc., were elevated 
above the waters of the sea at the close of the Paleeozore 
Period in Tasmania. 
If this be admitted—which can hardly be doubted—it fol- 
lows that there should be found throughout the area now 
occupied by Secondary and Tertiary “rocks a connected, 
although, perhaps necessarily, a greatly broken and wasted, 
representation of all the original rocks of the two great 
