« AnteriorContinuar »
Attorisma curvatum (Morris).
. costata (Morris).
Pachydomus antiquatus (Morris).
Eurydesma cor data (Morris).
Pterinea macroptera (Morris).
Terebratula cymbwformis (Morris).
Spirifer crebristria (Morris).
subradiatus (G. Sowerby).
avicula (G. Sowerby).
vespertilio (G. Sowerby).
Productus brachythasrus (G. Sowerby).:— subquadratus (Morris).
Littorina Jilosa (J. Sowerby).
Pleurotomaria Strzeleckiana (Morris).
■ nov. spec. (Morris).
Theca lanceolata (Morjis).
Bairdia affinis (Morris).
Trilobites—(Small impressions of, not exceeding half an inch).
The Third Epoch includes coal deposits, with their intervening shales and sandstones, in which were found —
Glossopteris Browniana (Brongniart).
Zeugophyllites elongatus (Morris).
The Fourth and last Epoch is marked by the occurrence of elevated beaches, in which are found, —
And by the organic remains of land animals, occurring in the limestone, caves, or alluvial deposits, and which are identified with—
The evidence above referred to shows,—
1. That the stratified rocks of New South Wales
and Van Diemen's Land, from mica-slate upwards, reach only to the variegated sandstone inclusively, that sandstone being incumbent upon the coal deposits in New South Wales and Van Diemen's Land.
2. That their thickness does not exceed 2200 feet,
in which sandstone alone is 1400 feet;— and, lastly,
3. That, though inconsiderable in thickness, and
limited in the number of the organic remains which they contain, the sedimentary rocks of New South Wales and Van Diemen's Land furnish, nevertheless, new evidence in support of those geological laws, which have been derived from the examination of Europe.
Comparing now the area of the crystalline with that of the sedimentary rocks, it is found, —
1. That in New South Wales the space occupied
by the crystalline is to that of the sedimentary rocks as 3 : 1.
2. That in Van Diemen's Land it is as 7 : 1.
A classification of all the mineral masses, whether unstratified or stratified, into two divisions, the one including rocks having more than sixty per cent, of silica, the other less than the above per centage, shows, —
1. That in New South Wales the area of granite,
protogene, hyalomicte, quartz rock, sienite, siliceous breccia, quartzose porphyry, siliceous slate, sandstone, and conglomerate, all containing above sixty per cent, of silica, is, to the area of eurite, felspathic porphyry, greenstone and basalt rocks, containing less than 60 per cent., as 4*1 : 1.
2. That in Van Diemen's Land, on the contrary, the
area of the first division is to that of the second as 1 : 3.
This inverse ratio of siliceous to non-siliceous rocks in the two colonies, while it decides the question of the relative agricultural character of soils of each colony, shows, in the mean time, the effects of the volcanic agencies, which appear to have operated on a more extensive scale in Van Diemen's Land than in New South Wales.
Indeed, the torn, rugged, furrowed, and contorted surface of the former colony, bears ample witness to the formidable revolutions produced by the eruptive greenstone and basalt, overwhelming, in succession, different members of the series, which then composed the consolidated crust, and sweeping away and burying a vegetation, of which no living traces are now left on the island.
But these changes have served only to render this island one of the most eligible spots on the face of the globe for the pursuits of agriculture: the irrupted greenstone yields an excellent soil, and the zigzag course of the chain of mountains forms naturally flatbottomed valleys, between which rises a table-land about 3800 feet, enclosing in crateriform lakes five reservoirs of water, covering, if the surface were united, an area of 200 square miles, and capable of irrigating all the adjacent lands available to cultivation.
New South Wales exhibits few records of irruptive igneous rocks, and preserves all its crystalline siliceous rocks in addition to the siliceous sedimentary ones, which in the course of ages have accumulated upon its surface.
This difference in the predominant kind of rocks, and in the configuration of the surface, will probably assign to each colony a different form of future prosperity.
New South Wales, by the nature of its soils, seems destined apparently to become a pastoral, Van Diemen's Land an agricultural country.
To hasten the development of that destiny, to pave the way, not only for a successful investigation of other branches of physical science, but to lead directly to the improvement of agriculture, and the success of commercial projects in various departments, a regular geological survey of the two colonies cannot be too strongly recommended; and such a survey as the science of the present day requires can only be accomplished by the aid of the Government, and by the