USEFUL METALS 



197 



States raiue from the eastern side of an imaginary line drawn 

 from Lake Winnepeg on the north to the eastern base of the 

 Knekirs, thence southward to the Rio Grande River. It will 

 IK- remembered t hat practically all of the gold in the United 

 States comes from the western side of the name line. 



(1) The Appalachian district stretches in a northeasterly 

 direction from Alabama on the south to Newfoundland on the 

 north, and may itself be subdivided into three distinct fields, 

 especially with respect to age and the character of the ores in- 

 volved. (1) The pre-Cambrian belt where the ores are largely 

 magnetites and specular hematites. These are especially 



FIG. 104. Map showing distribution of hematite and magnetite de- 

 posits in the United States. After Harder. (By permission of the Mac- 

 millan Company, from Ries' Economic Geology.) 



abundant in the Adirondack region, southeastern New York, 

 northern New Jersey, southeastern Pennsylvania and in Tennes- 

 see. (2) The Cambro-Ordovician ores, hematite and limonite, 

 are distributed along the great Appalachian valley, and even 

 abundantly in western New England. (3) The Clinton ore, 

 fossiliferous or oolitic, of Silurian age. These deposits are espe- 

 cially well developed in central New York, where they were first 

 discovered at Clinton, Oneida County, N. Y., and in Alabama. 

 The terranes of the Adirondack region are almost exclusively 

 pre-Cambrian. The exceptions are the occasional inliers of 



