THE LEAD REaiON. (539 



CHAPTER lY. 

 THE LEAD EEGION". 



Boundaries and Area. In Wisconsin, the Lead region may be 

 said to be bounded on the north by the northern outcrop of the Ga- 

 lena limestone, running parallel to the main watershed from the Mis- 

 sissippi to the Blue Mounds, as already described; on the west by the 

 Mississippi river; on the south by the state line; on the east by 

 Sugar river. These limits include all of the Lead region which has 

 ever been productive, as well as much that has never as yet proved so. 

 The area thus included which has been, or may hereafter become pro- 

 ductive, is necessarily that of the Galena limestone, which is about 

 1,776 square miles. 



Explanation of Mining Terms. For the enlightenment of the 

 readers of this report, who are unfamiliar with mining terms, the 

 following short explanation of expressions most frequently used in 

 the Lead region is offered. 



Range. This is probably the most indefinite term in use, and at 

 the same time, one which is universally applied. 1st. A range de- 

 notes a single, or several parallel crevices, containing useful ores or 

 minerals; vertical, or approximately so; seldom more than a few 

 yards apart; sometimes, but not necessarily, connected by quartering 

 crevices. Its length may vary from a few hundred feet to a quarter 

 of a mile or more; in short, so far as the crevice or crevices have 

 been connectedly traced, or there is a reasonable probability of such 

 connection. Thus, diflFerent parts of the same range often have dif- 

 ferent names siven them before the connection between them is 

 proved. This is a fruitful source of confusion. 2d. The term range 

 is also applied to horizontal bodies of ore, of which there may be 

 one, or several, superimposed upon one another; sometimes, but not 

 necessarily separated by unproductive layers of rock, limited in 

 length in the same way as a vertical range. 



Crevice. This term denotes a fissure in the rock, vertical or near- 

 ly so, but a few inches in width, of indefinite length, which may or 

 may not be filled with ores or minerals; when a crevice becomes very 

 small, less than an inch in width, it is called a seam. 

 Wis. Sub. — 44 



