The southern areas, viz., Peak and Darling Downs, etc., are older, agreeing with the lower volcanic of Victoria, which have been ejected through fissures, and have in no case a very extensive flow beyond the lines of fracture through which they issued. These may be referred to the Miocene Tertiary epoch. The rock masses forming both the upper and lower volcanic are basic in character, and may be all termed or grouped under the general term “dolorites.”
The volcanic soils of Queensland are those best adapted for the grazier and agriculturist.
To epitomise:—With the exception of the McKinlay Ranges, a line drawn parallel to the eastern coast, at a distance of 250 miles, would include all the palæozoic, metamorphic, granitic, trappean, and volcanic rocks represented in the colony, both coal groups lying within the same area.
The mesozoic and cainozoic systems occupy the surface area to the westward. The volcanic rocks follow the line of greatest elevation on the main watershed at altitudes from 1,500 to 2,000 feet above sea level. The chief granitic mass extends from Broad Sound to Cape York, with an occasional capping of “Desert Sandstone.” Westward from the Dividing Range, “Desert Sandstone” and the cretaceous and oolitic groups alternate one with the other to the extreme limit of the colony.
AREA OF FORMATIONS.
Estimating the entire extent of the colony at 600,000 square miles, a rough approximation to the areas occupied by the different geological formations is as follows:—
| Square Miles. | ||
| Valueless land, “Desert Sandstone” | 150,000 | |
| Scrubby and thickly timbered inferior pastoral, but valuable as containing coal, iron ore, &c. |
{ CarbonaceousMesozoic and Palæozoic |
} 24,000 |
| Fair pastoral, and valuable for its associated minerals and metals |
{ DevonianSilurian Metamorphic |
} 60,000 |
| Fair pastoral | Granitic | 114,000 |
| Good pastoral |
{ Cretaceousand Oolitic |
} 200,000 |
| First-class pastoral and agricultural |
{ AlluvialVolcanic Trappean |
} 52,000 |
| ——— | ||
| 600,000 | ||
Looking at the matter from an economical point of view, we find that one-fourth of the Colony of Queensland is valueless, whereas three-fourths furnish good pastoral land. Of this latter 60,000 square miles contain extensive and very valuable mines of gold, with numerous outcrops of copper and lead ores, to which may be added rich deposits of tin ore; 24,000 square miles are capable of producing illimitable supplies of coal and iron; 52,000 square miles are, as far as soil is concerned, best adapted for the agriculturist and squatter. In conclusion, it may be asserted that there is here a wealth of material resource which compares favourably with that of any other Australian colony.
THE GREAT BARRIER REEF.
North Queensland owes one of its chief claims to distinction to its numerous ports and harbours. In fact, the whole coast from Lady Elliott Island northwards to Cape York is one large harbour; protected as it is from the ocean swell by the Great Barrier Reef, a natural breakwater, extending for nearly a thousand miles, with a depth from ten to twenty fathoms, and a distance from the main land which varies from twenty to fifty miles. The sea outside is profoundly deep, and a few islets are found on the line of reef, also a few ship canals through the Barrier Reef. “The Great Barrier Reef of Australia; its products and potentialities,” by W. Saville Kent, F.L.S., is a splendid work, and beautifully illustrated. This work shows the reef to be full of marine wonders and is intensely interesting; its various forms of life and marine vegetation would fill volumes. The Great Barrier Coral Reef of Australia, the marvellous extent of which was first made known by Captain Cook, is one of the wonders of the universe. Its linear measurement is no less than 1,250 miles, extending from 9-1/2 deg. of south latitude to Lady Elliott’s Island, the most southern true coral islet in the chain or system. Its whole area lies within the territorial jurisdiction of Queensland, and the greater portion in North Queensland of which it forms one of the most valuable possessions. Raw material to the value of over £100,000 annually is obtained from the reefs and waters for exportation. The distance from the main land to the outer edge or boundary of this gigantic reef varies from ten or twelve miles to thirty. It is mostly formed of a chain of detached reefs and coral islets, many submerged or partially exposed at low water, with several openings, a few of which offer secure passage for large vessels.