The American Geologist, Volume 12Newton Horace Winchell Geological Publishing Company, 1893 Includes section "Review of recent geological literature." |
Overige edities - Alles bekijken
Veelvoorkomende woorden en zinsdelen
AMERICAN GEOLOGIST Auxology basin beds brachiopods Cambrian carbonate of lime Carboniferous character clay Coal Measures contains copper Corals Cordilleran sea Creek Cretaceous deposits described Devonian dikes Dinichthys district drift englacial Eocene epidote epoch erosion evidence exhibit fauna feet formation fossils genus Geological Survey GEOLOGIST glacial glacier gold gorges gravel hight hills ice-sheet inches Iowa iron lake land later limestone loess Louis limestone lower Magnesian magnetite mass mechanical sediments Mesozoic mineral mines Minnesota Missouri moraine mountain N. Y. Acad Newberry observed ocean Ohio origin Orthoceras osars Paleozoic paper plants plates Pleistocene portion present probably Prof protoconch region Report ridges river rocks sand sandstone Science shales shell side Silurian silver siphuncle species specimens square miles stages strata streams structure surface Tertiary thickness tion Tucumcari upper valley WARREN UPHAM Winchell
Populaire passages
Pagina 366 - ... as was taken by the remaining area in which calcium was being deposited. The area of the Cordilleran sea is given as 400,000 square miles, but it was probably 600,000, if not much more. It may be claimed that the area tributary to the Cordilleran sea was greater than I have estimated. The evidence, such as it is, is against such a view. As a whole I think the estimate of 17,500,000 years for the duration of Paleozoic time in the Cordilleran area is below the minimum rather than above it.
Pagina 350 - The total annual rainfall on the land of the globe, and the relation of rainfall to the...
Pagina 364 - ... 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...
Pagina 348 - Montana, and still further north into Alberta and British Columbia. During Ordovician, Silurian, Devonian and Carboniferous time this entire Mississippian region, except portions in Devonian time, appears to have been covered by a relatively shallow sea that was coextensive with the Appalachian sea and that communicated freely with the Cordilleran sea. During this same age, however, the Rocky mountain area of New Mexico, Colorado, Utah, Wyoming and Montana formed a more or less well defined boundary...
Pagina 366 - ... (21,000,000 years), or the area of denudation from 1,600,000 square miles to 24,000,000, — or three times the present area of the North American continent. In the estimate for the amount of chemical denudation the largest average is taken — 70 tons of calcium per square mile per annum — and the assumption made that all calcium derived from the adjoining drainage area was deposited within the Cordilleran sea.
Pagina 349 - 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.
Pagina 198 - The paleontology of the Cretaceous formations of Texas : The invertebrate paleontology of the Trinity division : Washington Biol.
Pagina 363 - ... amount of calcium, in these deposits, if they be 22 feet thick, is equal to the total amount of calcium in solution in the whole ocean at the present time. It follows from this that if the salinity of the ocean has remained the same as at...
Pagina 346 - Cordilleran seas, where 30,000 feet or more of sediments were deposited. In the Cordilleran sea sedimentation was practically uninterrupted (except during a short interval in middle Ordovician time) until towards the close of Paleozoic time. In the northern Appalachian sea it continued without any marked unconformity, from early Cambrian to the close of Ordovician time, and, south of New York, with relatively little interruption, until the close of Paleozoic time. Certain minor disturbances occurred...
Pagina 348 - ... of the latter to the northwest into the British possessions as far as the sixty-first, parallel. They were of a marine origin until towards the close of the period when a prolonged orographic movement elevated a large area of the continent above sea level and locally upturned the Cretaceous strata in the Rocky mountain area. The shoaling of the sea was followed by the formation of great inland lakes in which fresh water deposits succeeded the marine and estuarian sediments. Over the coastal regions...