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ANALYTICAL ABSTRACTS.
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of Southern Wisconsin. Within the quartzite are occasional layers of conglomerate. The different outcrops are apparently parts of a synclinal fold. As a result of the shearing much of the quartzite has been crushed, and sericite has developed.

Van Hise[1] considers the dynamic phenomena shown by the Baraboo quartzite ranges of Central Wisconsin. These rocks, indurated by cementation, 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 produced by the movement of the layers over one another is parallel to the bedding. In places Reibungs 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,[2] 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 microscopical examination shows that they possess all the characters of rocks cooled from fusion.

Smyth,[4] in 1893, describes the rocks of Gouverneur, N. Y. The gneiss gives evidence of mechanical deformation in the shattering of the quartz and

  1. ↑ 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.
  2. ↑ 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.
  4. ↑ 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 Transactions of the New York Academy of Sciences, Vol. XII., pp. 203-217.
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