The object of this paper is to explain the genesis of the limonite ores of the limestone valleys in central and eastern Pennsylvania, to show the original sources of the iron, the modes of its accumulation, and to account for its frequent occurrence along with more or less extensive bodies of white and parti-colored clays. The data and conclusions presented are based on field studies of the limonite ores of the limestone areas in the Great valley and in portions of Nittany valley.
The occurrence of limonite ores in Pennsylvania has been known a great many years; in fact, they have been employed in the manufacture of iron ever since that industry began in this country. They occur in every geological formation and in every county in the state, but this paper treats only of those in the limestone valleys of the central and eastern portions and the closely . . .