ANAL YTICA L ABS TEA CTS. 1 1 7 



of Southern Wisconsin. Within the quailzite are occasional layers of con- 

 glomerate. The different outcrops are apparently parts of a synclinal fold. 

 As a result of the shearing much of the quartzite has been crushed, and seri- 

 cite has developed. 



Van Hise ^ considers the dynamic phenomena shown by the Baraboo 

 quartzite ranges of Central Wisconsin. These rocks, indurated by cementa- 

 tion, exhibit all stages between massive quartzite showing microscopically 

 little evidence of interior movement, through a rock having in turn fracture 

 and cleavage, to one which is apparently a crystalline schist, but in thin 

 section still giving evidence of its fragmental origin. The schistosity pro- 

 duced by the movement of the layers over one another is parallel to the 

 bedding. In places Reibiings breccias have developed. At one point minor 

 faulting was noticed. These phenomena are more marked in the North Range 

 than in the South Range, and thus bear in favor of Irving's explanation of the 

 structure as a part of a single great fold in a set of layers 12,000 feet thick, 

 the North Range being on the leg of the fold, and thus requiring greater 

 readjustment of the beds than those on the South Range, which are near the 

 crown of the anticline. 



Winslow,- in 1893, places in the Archean the granites, porphyries, and 

 felsites of Missouri, and in the Algonkian the associated conglomerates, one of 

 them bearing the Pilot Knob iron-ore. 



Keyes,3 in 1893, holds that the granites of Maryland are eruptive, since 

 these rocks indiscriminately cut across the other igneous rocks of the region, 

 as well as the gneiss ; because they hold inclusions of the other rocks of the 

 region ; because the rocks cut show contact phenomena, and because a micro- 

 scopical examination shows that they possess all the characters of rocks cooled 

 from fusion. 



Smyth,'* in 1893, describes the rocks of Gouverneur, N. Y. The gneiss 

 gives evidences of mechanical deformation in the shattering of the quartz and 



'Some Dynamic Phenomena Shown by the Baraboo Quartzite Ranges of Central 

 Wisconsin, by C. R. Van Hise. Journ. of Geol., Vol. I., No. 4, pp. 347-355- 



^The Geology and Mineral Products of Missouri, by Arthur Winslow. From 

 " Missouri at the World's Fair." (Official Publication of the World's Fair Commission 

 of Missouri). 



3 Some Maryland Granites and Their Origin, by C. R. Keyes. Bull. Geol. Soc. of 

 Am., Vol. IV., pp. 299-304. 



" Petrography of the Gneisses of the Town of Gouverneur, N. Y., by C. H. Smyth, 

 Jr. Contributions from the Geol. Dept. of Columbia College. Reprinted from Trans- 

 actions of the New York Academy of Sciences, Vol. XII., pp. 203-217. 



