TIIICKNESS AND AREA OF THE APPALACHIAN COAL FORMATIONS.
In this estimate of the Appalachian coal areas, we are guided by Prof. Rogers, who has furnished the latest available information on the subject.
"The eastern half of the continent contains five great coal-fields, dis tributed at intervals from Newfoundland to Arkansas.
"The first, or most easterly, is that of the East British provinces,— Newfoundland, Nova Scotia, Cape Breton, and New Brunswick,—originally a wide coal-field, broken into patches by uplifts of the older strata and by the waters of the St. Lawrence Gulf. The surface covered by the coal measures of the provinces is probably about 9000 square miles, but appa rently only one-tenth of this area is productive in coal.
"The second, which I have called elsewhere the great Appalachian coal field, commences in Pennsylvania and extends southwest to near Tusca loosa, in Alabama. This includes several outlying lesser basins,—those, for example, of the anthracite coal in Eastern Pennsylvania. It has a total area of 70,000 square miles.
• "The third is the smaller coal-field of the centre of Michigan, equidis tant from Lake Huron and Lake Michigan. The area of this may be given at about 15,000 square miles. It is deficient in coal.
"The foUrth is the great coal-field lying between the Ohio and Missis sippi anticlinals, and spreading in the form of a wide elliptical flat basin from Kentucky north through Indiana and Illinois to Rock River. This possesses an estimated area of 50,000 square miles.
"The fifth and most west is a long and large coal-field, occupying the centre of the great basin of carboniferous rocks which spreads from the Mississippi and Ozark anticlinals west to the visible limits of the pakeozoic region, where it is overlapped by the Middle Secondary and Cretaceous deposits of the prairies. The northern limit of this coal-field is in Iowa, on the Iowa River; the southern is near the Red River on the western confines of Arkansas; and the total area of the great irregular basin is not less than 57,000 square miles.
"Summing up the several here defined, we perceive that the broad coal-fields of North America occupy the enormous space of at least 200,000 square miles, or more than twenty times as large a surface as that which includes all the known coal deposits of Europe, or probably of the Eastern Continent.