AMERICA. 121 



markable for titaniferous iron-ores. In the Huroniau are the great 

 deposits of hematite and magnetite of Lake Superior ; chromic iron- 

 ores seem to be characteristic. The distribution of ores in other rocks 

 is also noticed. W. W. 



Hfnt, Dr. T. S. Notes on the Geology and Economic Mineralogy of the 

 South-eastern Appalachians. Proc. Amer. Assoc, vol. xxii. B, 

 pp. 113-115 (abstract). 



. Geology of Southern New Brunswick. Proc. Amer. Assoc. 



vol. xxii. B. pp. 116, 117 (abstract). 



. Breaks in the American Pala3ozoic Series. Proc. Amer. Assoc. 



vol. xxii. B. pp. 117, 119 (abstract). 



-. On the crystalline Rocks of the Blue Ridge, and on their 



decomposed condition. Proc. Boston Nat. Hist. Soc. vol. xvi. 



part 2, pp. 116, 117. 

 These consist of hornblendic and micaceous schists, completely de- 

 composed to a depth of 50 feet and more, being changed to a reddish 

 unctuous clay, with interbcdded layers of quartz, showing the original 

 inclination of the rocks. The removal of the iron-oxide is said to be 

 the source of the large deposits of hydrous iron-ores found at the foot 

 of the Blue Ridge in the Appalachian valley. The decomposition is 

 supposed to have taken place in very ancient times, when there was a 

 highly carbonated atmosphere. To the N.E. an absence of decom- 

 posed rocks is held to be due to subsequent denudation, the soft parts 

 being swept away, and the unchanged rock exposed and glaciated. 



E. B. T. 



Irving, Prof. Roland. On the age of the Copper-bearing Rocks of 

 Lake Superior; and on the Westward Continuation of the L. 

 Superior Synclinal. Amer. Journ. scr. 3, vol. viii. pp. 4G-56, with 

 sketch map and section. 

 The Laurentian granitic and gneissoid rocks are overlain uncomfor- 

 mably by the Huronian, which are about 4000 feet thick. These are 

 succeeded conformably by the Copper-bearing rocks, both dipping at a 

 high angle : the latter series consists of traps, conglomerates, sand- 

 stones, &c., of an enormous thickness, the upper sandstones alone being 

 10,000 feet thick. Lying over these nearly horizontally in places are 

 Lower Silurian Sandstones. It is maintained that the traps are com- 

 formably interstratiiicd and have been tilted with the others, that the 

 Copper-bearing and Huronian series were once spread out horizontally 

 over one another, that they were disturbed by the same force and 

 received their present tilted positions at the same time, and that tlio 

 Copper-bearing series should rather be classed with the Archa3au than 

 with the Silurian. E. B. T. 



Jackson, \V. IT. Descriptive Catalogue of the Photographs of the 

 United-States Geological Survey of the Territories. United-States 



