462 Notices respecting Neiv Books. 



to the strata and to each other, and their changes, are all carefully 

 treated, and well illustrated with more than 60 cuts, besides maps. 

 The theoretical deductions as to the origin of the ores occupy 

 Chapter II. of this Part. The hypotheses of sublimation and of 

 thermal waters being objected to, the theory of oceanic deposition 

 and formation from the containing strata is treated in detail, and 

 illustrated by a highly suggestive map of the probable " Silurian 

 Interior Sea," with its currents and islands. Practical considera- 

 tions follow, as to prospecting and mining ; and an Appendix gives 

 some particulars as to the statistics of Copper-production at Mineral 

 Point. 



Part V. (pages 573-581) consists of an account of the " Quart- 

 zites of Barron and Chippewa Counties," compiled from the notes 

 of Messrs. Strong, Sweet, Brotherton, and Chamberlin. 



Part VI. (pages 583-615), by P. H. King, on the Geology of the 

 Upper Plambeau Valley, comprises the unfinished work of the late 

 Mr. Moses Strong ; and, though full of excellent detail, is rather 

 a report of progress than a complete monograph, the river-courses 

 alone having been examined in the limited period of Survey. The 

 Archaean (Laurentian) rocks are here exposed as granites, gneisses, 

 mica-schists, hornblende-schists, and other old rocks ; somegrana- 

 tiferous *, others with chlorite, kyanite, staurotide, tourmaline, 

 quartz, magnetite, <fec. The hydrology, topography, glacial features 

 (scorings, kettles, drift-ridges, till, boulders, &c), soil, and vege- 

 tation of the district are duly considered ; and a microscopical 

 examination of the Archaean rocks, by R. D. Irving, is added 

 (pp. 616-621). 



Pages 623-714 contain Part VII., treating of the " Crystalline 

 Rocks of the Wisconsin Valley," by R. D. Irving and C. R. 

 Vanhise. In vol. ii. these rocks were briefly described as far as 

 then observed ; further field-work by members of the Survey has 

 extended the Geological Map and increased the collections. The 

 results are here shown in one general Geological Map and eight 

 sketch-maps of successive portions of the valley, with accompany- 

 ing notes. A tabulation of the results of Mr. Vanhise's micro- 

 scopic study of the crystalline rocks of each of these districts 

 supplies the number of the specimen f , a reference to the pages in 

 vol. ii., the name of the rock and of the place, the number of the 

 Land-section, the Town, and the Eange on the Sketch-map, the 

 macroscopic description of the rock, and its constituents as deter- 

 mined by the microscope. Granites (hornblendic, augitic, &c), 



* The use of the base word " gametiferous " in the Keport is as bad 

 as the other bastard word " diamondiferous," in circulation among our 

 South-African colonists. 



t The stated numbers of the specimens are the original collection 

 numbers ; and corresponding specimens " will be found in the Cabinets of 

 the State University, and of the Wisconsin Academy of Sciences, and, 

 less completely, in those of the State Normal Schools, of Beltoit, Racine, 

 Ripon, and Milton Colleges, and of Lawrence University." 



