304 Notices respecting New Books. 



portion of the rock-material collected by the Survey in Central 

 Wisconsin (pp. 637-642). 



Part IV. (pp. 643-752) gives an account of the geology and topo- 

 graphy of the Lead Region, by Moses Strong, with many illustra- 

 tions. This is the south-western corner of Wisconsin, in the angle 

 between the Wisconsin river on the north and the Mississippi on 

 the west, with Illinois on the south. The plan of surveying, list of 

 elevations, topography, including drainage and surface-features, are 

 noted and described. The diminution of river-water is noticed as 

 due probably to the removal of forests. Many old water-mills now 

 stand neglected ; but at the same time some mines have been 

 reopened and profitably worked, owing to the lessened quantity of 

 underground water. The surface-geology shows soils, subsoils, and 

 drift, which are duly noticed ; and the deeper geological formations 

 are described as fully as space permits. They are Potsdam Sand- 

 stone, Lower Magnesian Limestone, St.-Peter's Sandstone, Tren- 

 ton (buff and blue) Limestones, with ores of zinc and lead, Galena 

 Limestone (dolomite), with ores in nests, sheets, &c, and the Cin- 

 cinnati group. The " Lead Eegion " proper is then described 

 (pp. 689 &c), namely the area of the exposure of the Galena 

 Limestone, about 1776 square miles. The local mining terms are 

 explained : and the mineralogy of the district is shown by a list of 

 classified local minerals. " The minerals appear to have been 

 deposited in the following general order : — 



Galenite. 



I 

 Sphalerite. 



I 

 Dolomite. Calcite. 



i 



Pyrite. Marcasite. Chalcopyrite. 

 Barite. 



Calcite. 



I 



^ ^ 



Cerussite. Smithsonite. Malachite. Azurite." 



Exceptions, however, and obscure conditions are far from being 

 uncommon. 



The present condition of the mines and diggings in the various 

 districts (pp. 694 &c.) is described in some detail ; and the statistics 

 of all the mineral produce are given. 



A full, clear Index completes this volume, which is well worthy 

 of every geologist's consideration and study. Being a highly praise- 

 worthy production, at the hands of the geologists, artists, printers, 

 and all concerned, it brings honour to the statesmen of Wisconsin, 

 who are wise enough to have a good Geological Survey, and liberal 

 enough to get it done in a creditable manner. 



