Bulletin of the United States Geological Survey, Issue 86

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U.S. Government Printing Office, 1892

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Page 73 - ... previously formed rocks of the same age, both sedimentary and igneous, as is shown by the case of the knob of conglomerate already mentioned. The minute banding of the ore and jasper can hardly be explained by any other than the action of segregating forces in an igneous rock. The authors are then disposed to regard the specular and magnetic oxide of iron as a purely igneous product, in some instances poured out, in others sublimed, from the interior of the earth. Where the ores are in a state...
Page 69 - ... grains, with small specks of iron disseminated, and large, rounded masses of the same material inclosed, constituting a conglomerate. This bed was...
Page 22 - ... is patiently and continuously to follow the outcrop of each important mass in all its windings, as far as it can be traced, until it becomes covered up by superior unconformable formations, is cut off by some great dislocation, or disappears by thinning away to nothing.
Page 5 - Price 10 cents. 65. Stratigraphy of the Bituminous Coal Field of Pennsylvania, Ohio, and West Virginia, by Israel C. White. 1891. 8. 212pp. 11 pi. Price 20 cents. 66. On a Group of Volcanic Rocks from the Tewan Mountains, New Mexico, and on the occurrence of Primary Quartz in certain Basalts, by Joseph Paxson Iddings.
Page 4 - Marcon. 1884. 8. 184 pp. Price 10 cents. 8. On Secondary Enlargements of Mineral Fragments in Certain Rocks, by RD Irving and CR Van Hise.
Page 441 - I. Laurentian : To be confined to all those clearly lower unconformable granitoid or syenitic gneisses in which we never find interstratified bands of calcareous, argillaceous, arenaceous and conglomeratic rocks. II. Huronian : To include 1. The typical or original Huronian of Lake Superior and the conformably or unconformably, as the case may be overlying upper copper-bearing rocks. 2. The Hastings, Templeton, Buckingham, Grenville and Rawdon crystalline limestone series.
Page 425 - The contact-metamorphism produced in the adjoining mica-schists and limestones by the massive rocks of the " Cortlandt series,
Page 194 - Abstract of an Introduction to the Final Report of the Geological Surveys made in Wisconsin, Iowa, and Minnesota, in the years 1847, 1848, 1849 and 1850, containing a Synopsis of the Geological Features of the Country, David D.
Page 191 - On the Age of the Copper-bearing Rocks of Lakes Superior and Huron, and Various Facts Relating to the Physical Structure of Canada"; Rept.
Page 80 - Superior. portion of the shores of lake Superior, and in conjunction with the trap rocks constituting the highlands between that lake and lake of the Woods. From these highlands it stretches a little east of lake Winnipeg, far to the northwest, finally constituting the immense "barren grounds

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