258 APPENDIX. 



and Wisconsin. It may, probably, be obtained along the 

 head-waters of the western and northeastern tributaries of the 

 Illinois River. 



" BUILDING-STONE. 



" 1 was, for a time, in doubt in regard to the value of the 

 Wisconsin limestone as a building material. Where it has 

 numerous nodules of chert distributed through its mass, it 

 weathers unequally, the nodules become detached, and its 

 beauty and value as a building-rock are much lessened. 

 This occurs chiefly in the superior portion of the upper beds ; 

 that is, over the southern portion of the surveyed district. 



" Much of the limestone that is taken from the diggings 

 crumbles, also, on being exposed to the weather ; yet a por- 

 tion of the formation will yield some of the best quarries in 

 the world, and several excellent ones are already opened. 

 For example, on the Sinsinnewa Mound, at Mineral Point, 

 at the Four Lakes, and (but not so good) on the Peccaton- 

 nica. This excellent building-stone chiefly occurs in the 

 lower portion of the upper beds of the cliff limestone, and 

 also in the lower beds of the ' Missouri limestone.' It is of 

 a beautiful uniform light-yellow color, compact, fine-grained, 

 sharp-angled, capable of receiving a handsome finish, and, if 

 well selected, calculated to endure, uninjured, for ages. It 

 is very readily quarried in square blocks from six inches to 

 a foot in thickness ; can be obtained, however, double or 

 treble that thickness, and of any required horizontal extent. 

 The labor of quarrying is light, in consequence of the rock 

 being exposed in cliffs, so as to preclude the necessity of 

 excavation. 



" In a recent geological notice from England, it is stated 

 that Mr. Do la Beche, in conjunction with Mr. Barry and the 



