Political and commercial geology and the world's mineral resources

by Unknown

GEOLOGICAL DISTRIBUTION

Coals are found in the sedimentary deposits of several geological eras: Paleozoic, Mesozoic, and Tertiary. The Paleozoic era, embracing the Carboniferous period, is by far the most important as regards quality and availability of its coal resources; but the lower-grade and chiefly lignitic coals of the Mesozoic and Tertiary are of great importance locally, and there are enormous reserves that exceed in quantity the generally higher-grade coals of the earlier periods.

The geologic distribution of coal is described in “The Coal Resources of the World,” the most important and comprehensive compilation on coal reserves ever made, which was undertaken by the Executive Committee of the Twelfth International Geologic Congress, held in Canada in 1913. As the compilation was made with the assistance of geological surveys and mining geologists of the several countries of the world, it is cited in this paper as authoritative on geologic distribution and resources.

The geographic distribution of the chief coal fields of the world is shown in [Plate II].

In North America the most important coals in the Central and Eastern part are of Paleozoic age, but in the Rocky Mountain region vast quantities of coal occur in the Cretaceous (Mesozoic) strata. In the Gulf province and in the Northern Great Plains province of the United States, which extends into Canada, are coals of Triassic (Mesozoic) age that are relatively unimportant at present.

In beds of the Eocene period of the Tertiary era are large deposits of brown lignite locally converted by mountain-building forces into bituminous and semi-bituminous coal, and also a little anthracite under difficult mining conditions. Such locally altered beds are found in the State of Washington, in British Columbia, and in Alaska.

The limited coal resources of South America, in those deposits east of the Andes and in southern and eastern Brazil, are of Paleozoic age. Small areas of Tertiary coals are found in southern Argentina and in Chile.

Key to Plate II.

World’s Coal Reserves as of 1916—Coal Fields in Solid Black.

1. Countries possessing coal reserves of the first magnitude (4,000,000 million to 1,000,000 million tons): The United States (3,527,000 million), Canada (1,234,000 million), and China (1,500,000 million).

2. Countries possessing coal reserves of the second degree of magnitude (500,000 million to 100,000 million): The British Isles (189,533 million), Germany (before the war) (423,356 million), Siberia (173,879 million), and Australia (165,572 million).

3. Countries possessing coal reserves of the third degree of magnitude (80,000 million to 16,000 million tons): France (before the war) (17,583 million), Alaska (16,293 million), Colombia (27,000 million), Austria-Hungary (before the war) (55,553 million), Russia in Europe (before the war) (60,106 million), India (79,001 million), Indo-China (20,000 million) and South Africa (56,200 million).

4. Countries possessing coal reserves of the fourth degree of magnitude (16,000 million to 6,000 million tons): Spain (8,768 million), Japan (7,970 million), Belgium (11,000 million), Spitzbergen (8,750 million).

5. Countries possessing coal reserves, but of inferior magnitude (less than 4,000 million tons): Brazil, Argentina, Chile, Peru, Ecuador, Venezuela, Greenland, Holland, Denmark, Sweden, Italy, Bulgaria, Turkey, Greece, Roumania, Asia Minor, Persia, Arabia, various islands of Malaysia and various countries in Africa. Coal fields shown in black—country not shaded.

Plate II.—Geographical distribution of the coal deposits of the world, and relative reserves. By F. F. Grout.

In Europe the principal coal deposits occur in the Carboniferous system, either in the upper or the lower part. The Lower Carboniferous is the principal series in which coals occur in Scotland, whereas the most important coals in England and in Wales lie in Upper Carboniferous rocks. In northern France, in Belgium, and in Westphalia, Germany, the middle Carboniferous measures contain the most important reserves. Mesozoic coals are found in northern Australia and in central France. The lignites or brown coals of middle Europe are locally very important in Germany; those of Austria are found in numerous small but thick deposits of the Tertiary age.

Fig. 3.—Coal output of the chief coal-producing countries, 1880-1916.

The principal coal resources of Africa are in the southern part of the continent and are chiefly in deposits whose ages range from Carboniferous to Triassic.

In Asia the coal fields are not well defined. There are coal basins of note in India and China. In China important coals are found in the Upper Carboniferous. Coals of the Lower Carboniferous are found east of the Urals and also in Turkestan. In Japan the Mesozoic coals are important. Tertiary coals are widely distributed in Asia but are not high-grade nor of importance.

It may be safely stated that geological reconnoissance has covered the world so well that further development is not likely to disclose coal resources of great magnitude not now known with more or less exactitude. Estimates of resources of some regions will undoubtedly be revised many times, especially those of reserves in the middle portion of Africa, in South America, and China.