. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . is the most usual structure ofthe coal beds of Schuylkill County,fig. 46, and hence it follows thatthat county contains a much greateramount of mineral, in proportionto the superficial area, than any other district in the United whole county is but a succession of wave4ike elevations, withnarrow intervening valleys, all of which are full of the valuablemineral for which the region is so remarkable. Valleys of erosionare formed by the actio
. The pictorial sketch-book of Pennsylvania, or, Its scenery, internal improvements, resources, and agriculture, populary described . is the most usual structure ofthe coal beds of Schuylkill County,fig. 46, and hence it follows thatthat county contains a much greateramount of mineral, in proportionto the superficial area, than any other district in the United whole county is but a succession of wave4ike elevations, withnarrow intervening valleys, all of which are full of the valuablemineral for which the region is so remarkable. Valleys of erosionare formed by the action of water. Imagine a nearly level plain, andthen, at one end of it let a stream of water issue forth : in a compa-ratively short time, with the assistance of snows and rains, and alter-nate dry seasons, it will scoop out a hollow similar to fig. 47, while,in course of time, it will form a deep valley, surrounded with highelevations, or table-lands. The AUeghanies have, for the most part,been scooped out in this manner, and the debris deposited in thetable-flats sloping out from its loftier ranges. ANTHRACITE COAL FORMATION 155. ll.^iL^>Avm%M\.\i
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Keywords: ., bookcentury1800, bookdecade, booksubjectminesandmineralresources
