Bulletin of the United States Geological SurveyThe Survey., 1896 |
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Página 5
... Potomac Run .... Exposures at Potomac church Section on Potomac Run near Potomac church Exposure at the railroad bridge on Potomac Run Exposures on the Telegraph road at Potomac Run .. Exposures on the Woodchopping road ... Exposures ...
... Potomac Run .... Exposures at Potomac church Section on Potomac Run near Potomac church Exposure at the railroad bridge on Potomac Run Exposures on the Telegraph road at Potomac Run .. Exposures on the Woodchopping road ... Exposures ...
Página 12
... Potomac River , the name " Potomac " has been pro- posed for them by Mr. W. J. McGee , and this name will be used in this report . It would seem that Professor Rogers was induced , both by the gen- eral geologic character of the Potomac ...
... Potomac River , the name " Potomac " has been pro- posed for them by Mr. W. J. McGee , and this name will be used in this report . It would seem that Professor Rogers was induced , both by the gen- eral geologic character of the Potomac ...
Página 13
... Potomac beds between Chesterfield Station , in Caroline County , and Massaponax Creek , in Spottsylvania County . On the geologic map of the Virginias , which he prepared long after the publication of these reports , he colors as ...
... Potomac beds between Chesterfield Station , in Caroline County , and Massaponax Creek , in Spottsylvania County . On the geologic map of the Virginias , which he prepared long after the publication of these reports , he colors as ...
Página 14
... Potomac beds were laid down in a period decidedly more recent than that in which the Middle Secondary strata of Rogers were deposited . It is proposed to give descriptions and illustrations of these fossil plants in a future publication ...
... Potomac beds were laid down in a period decidedly more recent than that in which the Middle Secondary strata of Rogers were deposited . It is proposed to give descriptions and illustrations of these fossil plants in a future publication ...
Página 15
... Potomac material can be seen . In the most southern exposure on the Nottoway the top of the Potomac is barely reached by the deepest waterways . The eastern margin of the pre - Cambrian rocks is often at the head of tide water in the ...
... Potomac material can be seen . In the most southern exposure on the Nottoway the top of the Potomac is barely reached by the deepest waterways . The eastern margin of the pre - Cambrian rocks is often at the head of tide water in the ...
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Términos y frases comunes
acid apatite augite beds biotite bluff Bull California Cambrian Carboniferous chlorite clay balls Coal cobbles color Contains plagioclase County Creek Cretaceous deposits Describes the occurrence Devonian dike Discusses east Eocene erosion exposures feldspar figs folio fossils Geology Glacial gneiss gold granite gravel gray groundmass H₂O Harris hills hornblende Iowa iron James Jour K₂O Kansas kaolin Keyes L. G. Eakins Lake layers lignite limestone London magnetite masses material Matthew Merrill miles Miller and Gurley minerals Missouri moraine mottled Mountain Newberry olivine orthoclase Paleontology-Continued Paleozoic Paris plagioclase Pleistocene porcelain portion Potomac formation pottery pre-Cambrian Proc quartz quartzite record region Rept Rhyolite River rocks sand sandstone sandy clay Scudder Silurian SiO2 species stones strata Surv Tertiary TiO2 Trace Trans Turner U. S. Geol Ulrich Undet Valley W. F. Hillebrand Weed and Pirsson Whiteaves Whitfield Winchell and Schuchert
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Página 29 - Friedel ° indicates a means for determining the true weight of water lost by minerals behaving like the zeolites, even without collecting the water lost, namely, by driving out of the dehydrated and weighed mineral, under proper precautions, any air it may have absorbed in the process of drying and cooling, and collecting and measuring this air and thus finding its weight, which, added to the apparent loss, gives the true contents in water.
Página 22 - CRUSHING. For accurate analyses the use of steel power crushers and mortars is out of the question because of the danger of contamination by particles of metal and the impossibility of cleansing the roughened surfaces after they have been in use a short time. Extraction, by the aid of a magnet, of steel particles thus introduced into the powder is quite inadmissible, since the rocks themselves, almost without exception, contain magnetic minerals.
Página 61 - If, therefore, on evaporation of the filtrate, much iron is indicated, the gelatinization may well be due to olivine alone or in part, and then the quantitative relation of silica to iron plus magnesium should be ascertained. It must also be borne in mind that any other very soluble silicates present will be more or less affected, and that apatite is largely or wholly dissolved. It is possible that still more dilute nitric or perhaps some other acid may exert a slighter solvent action on olivine...
Página 20 - Survey was there to be found in the light of modern methods, a satisfactory exposition of the procedures to be followed or the precautions to be observed, especially in the search for some of the rarer constituents or those which, without being rare, have been of late years recognized as occurring persistently in small amounts. It was not the intention to .make the chapter on rock analysis in...
Página 28 - It had regained 1J per cent of its original weight, although the desiccator was tightly closed and the crucible covered, showing apparently a drying power superior to that of the acid. A specimen of tyrolite was found on one occasion to lose 10.34 per cent at 280°, and on another occasion 14.33 per cent.
Página 49 - ... as ZrO2. Certainty as to its identity can be had by again bringing it into solution, precipitating by ammonia, dissolving in hydrochloric acid, evaporating to a drop or two, and testing with turmeric paper or by a microchemical reaction. With the very smallest amounts no color can be obtained by this turmeric-paper test, which, however, responds readily to as little as 1 milligram of dioxide and with proper care for as small an amount as 0.3 milligram (Dr.