214 GEOLOGY. 



308. Amount of Coal. The amount of coal in the prin- 

 cipal coal-fields in the world has been estimated by Pro- 

 fessor H. D. Rogers as follows : 



Belgium 36,000,000,000 tons. 



France 59,000,000,000 



British Isles 190,000,000,000 



Pennsylvania 316,000,000,000 



Appalachian coal-field 1,387,000,000,000 



Indiana, Illinois, and Kentucky 1,277,000,000,000 



Iowa, Missouri, and Arkansas 739,000,000,000 



Total amount in North America.... 4, 000, 000, 000,000 

 The anthracite of this country was first introduced into 

 use in blacksmithing by Judge Obadiah Gore, a Con- 

 necticut blacksmith, in Wilkesbarre, a few years less than 

 a century ago; but it did not come into common use 

 until between thirty and forty years since. In 1820 the 

 amount worked in Pennsylvania was only 380 tons. Its 

 use, however, from that time increased rapidly, and in 

 1847 that state furnished over three million of tons, be- 

 sides two million of bituminous coal. The United States 

 produced in 1857 ten and a half million of tons ; and if 

 our annual consumption should be twelve million of tons, 

 it is calculated that there is coal enough in North Amer- 

 ica to last us 333,333 years. 



309. Extent of Coal-fields. Coal-fields vary much in 

 extent, the largest in the world being in North America. 

 The most extensive of all is the Appalachian. This oc- 

 cupies parts of Pennsylvania, Ohio, and Virginia, the 

 eastern portion of Kentucky and Tennessee, and extends 

 down into Alabama. It covers an area of 80,000 square 

 miles, 60,000 of this being available. This is about ten 

 times as great a space as that occupied by all the pro- 

 ductive coal-fields of Great Britain. Then there is the 

 Indiana, Illinois, and Kentucky coal-field, covering a 

 space of 50,000 square miles, and the Iowa and Missouri 

 coal-field, 60,000. The New England coal-field occupies 

 an area of only about 600 square miles. 



310. Arrangement of the Coal-strata. The coal is in 



