The American Geologist: A Monthly Journal of Geology and Allied Sciences ..., Band 7Geological publishing Company, 1891 |
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America AMERICAN GEOLOGIST anticlinal Archæan augite basin beach beds bryozoa calyx Carbon Carboniferous Catskill central clay coal columella conglomerate contains Coutchiching creek Cretaceous crinoids crystalline Cyclopteris Dakota deposits depth developed Devon Devonian diabase drift dyke east Ebenezer Emmons elevation Emmons erosion Europe extend fauna feet formation formed fossils fovea genera genus Geol geologists glacial glacier gneiss granite gravel hills ice-sheet Keewatin known lake Agassiz later Laurentian limestone lode lower miles mineral Minnesota moraines mountain nearly Neocomian northern observations occur Ohio outcrop palæontologist paleozoic paper pebbles Penn'a plates portion present probably Prof quartz region ridges river rocks sand sandstone schists seam septa shales silica Silur Silurian slate species specimens strata structure surface Surv tabulæ Taconic system Tertiary Texas thickness thin tion unconformity upper valley wall York
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Seite 130 - On the geology and physiography of a portion of northwestern Colorado and adjacent parts of Utah and Wyoming, by CA White.
Seite 178 - It is pisolitic in structure, and, like all bauxite, varies more or less in color and in chemical composition. At a few places it is so charged with iron, that attempts have been made to mine it for iron ore. Some of the samples from these pits assay over 50 per cent. of metallic iron. This ferruginous kind is exceptional, however. From the dark-red varieties it grades through the browns and yellow to pearl-gray, cream-colored, and milky-white, the pinks, browns and grays being the more abundant.
Seite 11 - I have ever yet heard of, proved the existence of a nation here who knew the use of iron. I have never heard even of burnt bricks, though they might be made without iron. The statue you have been so kind as to send me, and for which I beg you to accept my thanks, would, because of the hardness...
Seite 354 - For anything that geology or palaeontology are able to show to the contrary, a Devonian fauna and flora in the British Islands may have been contemporaneous with Silurian life in North America, and with a Carboniferous fauna and flora in Africa.
Seite 136 - 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.
Seite 209 - ... Classification 189 Concluding Remarks 191 INTRODUCTION. It has long been known that the crystalline schists of the Coast Ranges of California contain in considerable abundance and widely distributed a blue amphibole, related in many of its characters to glaucophane. This fact was first announced by Dr. Becker in his report* on the Quicksilver Deposits of the Pacific Slope, in which he gives brief notes on the characters of the mineral, regarded by him as normal glaucophane.
Seite 221 - The Epoch of the Mammoth and the Apparition of Man upon the Earth, by James C.
Seite 185 - Dakota consisted of vast lobes, one of which reached from central and western Minnesota south to central Iowa. This lobe in its maximum extent ended near Des Moines, and its margin was marked by the Altamont moraine, the first and outermost in the series of eleven distinct marginal moraines of this epoch which are recognizable in Minnesota. When the second or Gary moraine was formed, it terminated on the south at Mineral ridge in Boone county, Iowa. At the time of the third or Antelope moraine, it...
Seite 178 - The exposures vary in size from an acre to twenty acres or more, and aggregate over a square mile. This does not in all probability include the total area covered by bauxite in the counties mentioned, for the method of occurrence of the deposits leads to the supposition that there are others as yet undiscovered by the Survey. In thickness...
Seite 203 - On the Physical Cause of the Change of Climate during the Glacial Epoch.