Bulletin - United States Geological Survey, 80-83호

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425 페이지 - There seems, then, no escape from the admission that neither physical geology nor palaeontology possesses any method by which the absolute synchronism of two strata can be demonstrated. All that geology can prove is local order of succession. It is mathematically certain that, in any given vertical linear section of an undisturbed series of sedimentary deposits, the bed which lies lowest is the oldest. In...
22 페이지 - Report of the progress of the Geological Survey of the State of Virginia for the year 1840.
213 페이지 - Descriptions of new organic remains collected in Nebraska Territory in the year 1857, by Dr. FV Hayden, geologist to the exploring expedition under the command of Lieut. GK Warren, Top. Engr. US Army, together with some remarks on the geology of the Black Hills and portions of the surrounding country.
396 페이지 - ... among which the principal are, that rocks may be divided into two great classes, the stratified and the unstratified ; that of the former some contain organic remains and others do not; and that the...
28 페이지 - Explorations under the War Department. Explanations of a Second Edition of a Geological Map of Nebraska and Kansas, based upon Information obtained in an Expedition to the Black Hills, under the Command of Lieut. GK Warren.
267 페이지 - The principles involved in correlations made by use of fossils are purely biologic and are intimately concerned with the laws of structure and growth of the individual, with the effects of environment and geographical distribution, with the laws of heredity and evolution, and with the laws of relationship of organisms to each other and to geologic time. The discussion of these matters would be out of place here; but it may be said that the great advance attained in the accuracy and in the general...
413 페이지 - Calcareous deposits, as would naturally be supposed, have been found to be more persistent and more uniform in the character of their fossil contents ; but these, over some portion of their extent, have often been invaded by argillaceous and arenaceous sediments, and the fauna is found to be in a greater or less degree influenced by such circumstances.
235 페이지 - The fades of the Devonian Flora in America is very similar to that of the same period in Europe, yet the number of identical species does not seem to be so great as in the coal-fields of the two continents. This may be connected with the different geographical conditions in these two periods ; but the facts are not yet sufficiently numerous to prove this.
400 페이지 - ... clays had their origin in the east, southeast, and northeast, producing a turbid condition in the waters of these parts during long intervals, and the formation of chemical deposits. In New York we are evidently upon the margin of this primeval ocean, as indicated in the character of the deposits as well as organic remains; the southwest unfolds to us that portion where greater depth and more quiet condition prevailed.
131 페이지 - ... in nearly all the exposures from the Balcony falls to Thornton's gap, as well as in various other places, exhibits vague, fucoidal and zoophytic impressions on the surfaces of bedding, together with innumerable markings at right angles to the stratification, penetrating in straight lines to great depths in the rock, and from their frequency and parallelism determining its cleavage in nearly vertical planes. These markings are of a flattened, cylindrical form, from...

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