The Journal of Geology, Band 1;Bände 13-14University of Chicago Press, 1893 Vols. for 1893-1923 includes section: "Reviews." |
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acid anorthosite Appalachian Archean augite basal basin beds boulders calcareous Cambrian carbonate of lime Carboniferous character chemical coal coast conglomerate contain Cordilleran Cretaceous crystalline crystals deposits diabases diallage district drainage drift eastern erosion eruptive evidence exhibit fault feet feldspar folding formation fossils gabbro Geol Geological Survey geologists glacial epoch glacier gneiss granite gravel hornblende Huronian igneous iron and manganese Jour Keweenawan Lake Superior land later Laurentian limestone lower magma manganese mass material metamorphism miles mineral moraine mountain observations occur ocean olivine origin oxide Paleozoic petrographical phonolite plagioclase porphyritic portion pre-Cambrian present probably Professor pyroxene quartz quartzite region rhyolites ridge Riga Schist river rocks sand sandstone schist sections sedimentary sediments sheet Silurian slope specimens strata streams structure surface terraces Tertiary theory thickness tion unconformity upper valley volcanic
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Seite 811 - Notes on the Cambrian rocks of Pennsylvania and Maryland from the Susquehanna to the Potomac, by CD \Valcott.
Seite 668 - ... square miles, — or one-third of the land area of Europe. In North America nearly one-half of the total area was covered by the Paleozoic sea ; in South America it was considerably less ; and we know too little of the Asiatic and African continents to place any estimate upon their Paleozoic areas. I think, however, if we take one-fourth of the present land area as the territory covered by the Paleozoic seas we shall be considerably within the actual amount, even if we add to the surface of the...
Seite 276 - The pieces of limestone are so markedly different from the calcareous bed enclosing them that they cannot be confounded with it. The rock fragments are of unequal distribution in the deposit, both laterally and vertically, sometimes composing almost half of it, and sometimes being almost entirely absent. They vary from a fraction of an inch to several inches in diameter and are indiscriminately mixed.
Seite 647 - I obtain 113 tons as the total amount of matter in solution discharged into the Atlantic basin per annum from each square mile of area drained into it. Of this 49 tons consist of carbonate of lime and 5.5 tons of sulphate and phosphate of lime.4 Mechanical sediments.
Seite 425 - 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 645 - Our knowledge of the conditions north of the 55th parallel is limited by the want of accurate geologic data. If Cambrian and Carboniferous rocks were not deposited in the Mackenzie river basin and also on the eastern side of the area now covered by Cretaceous strata, the inference is that during Cambrian and Carboniferous time there was a land area to the east and north of the northern Cordilleran sea that may have been tributary to the latter.
Seite 642 - ... in partially enclosed seas or mediterraneans and on the borders of the continental plateau. The former is particularly true of the sedimentation of the Cordilleran and Appalachian seas and the broad Mississippian sea. The close of the prolonged period of Paleozoic sedimentation was brought about by what Dana has termed the "Appalachian revolution.
Seite 669 - ... of carbonate of lime, we have 52,500,000 square miles, over which there is at the present time a deposition of the carbonate of lime being made. We have roughly estimated that in Paleozoic time the area of the Paleozoic sea, in whic.h deposits were being accumulated, was over 13,000,000 square miles. It does not appear that there is any good reason to suspect that the area of deposition of the carbonate of lime in the open ocean during Paleozoic time was not fully equal to that of the present...
Seite 649 - The conditions of the deposition of the carbonate of lime are less clearly understood than those governing mechanical sediments, and I shall enter upon the discussion of them at considerable length. There are three methods by which it usually is considered that it may be deposited: 1. Agency of organisms. 2. Chemical precipitation. 3. By mechanical methods. It is the general opinion of geologists that limestone rocks are the result almost entirely of the consolidation of lime removed from the sea...
Seite 671 - If the estimated rate of the deposition of coral limestones — five feet in 1,000 years — given by Prof. James D. Dana is correct, the 19,000 feet of Paleozoic limestone in central Nevada would have required 3,800,000 years to have accumulated under the most favorable [local conditions surrounding a coral reef. With the exception of large deposits of corals in Devonian rocks no appearance of a coral reef is recorded in the Cordilleran area.