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abundant acid alteration alumina amount analyses anticline associated beds biotite Bull calcite carbonate cassiterite cent Ceylon chalcocite chalcopyrite chemical chlorite coal composition constituents contact metamorphic contains copper country rock crystals depth described dikes diorite district Dolores domes Economic Geology epidote evidence fault feet feldspar fissures fluorite fractures galena gangue garnet geologist gneiss grams granite graphite greisen gypsum hornblende igneous rocks important inches intrusive iron iron-bearing formation kaolin lime lime-silicate limestone lode magma magnetite mass metallic metamorphosed mica microscopic miles minerals mining molecules monzonite occur ore-deposits origin orthoclase oxide pegmatite phase porphyry present probably production pyrite pyroxene pyrrhotite quartz quartzite region replacement saline salt schists sedimentary sediments sericite shale silicates silver solutions specific gravity sphalerite stage structure sulphides sulphur surface temperature tin deposits tion topaz tourmaline turquoise U. S. Geol U. S. Geological Survey volcanic wollastonite zinc zone
Page 111 - Survey collection ; the American Museum of Natural History ; the Academy of Natural Sciences of Philadelphia; the Museum of Comparative Zoology in Cambridge, Massachusetts, including the collection of Messrs.
Page 630 - In practice the topographer first decides the relation of the new station with reference to the fixed points, whether it is within the great triangle or in one of the segments or outside the great circle. He then determines the position of the point sought with reference to one line (if within one of the segments or without the great circle by Rule 2 or 3); it then follows from Rule 1 that it must be on the corresponding side of the other two lines. Finally, he estimates the relative distances of...
Page 576 - ... streaks of sand even in the producing zone that add further confusion to correlation. There is a shallow sand that is productive of oil in section 27, Martin township that may be comparable to one of the shallow Clark county sands. Its extent is very limited. DETAILED STRUCTURE OP THE DISTRICT. Owing to the irregular deposition of sands and shales it was found impossible to correlate and contour any sand beds definitely except the top lens of the Robinson sand which is somewhat persistent over...
Page 364 - Well-defined anticlines alternating with synclines. (c) Structural terraces. (d) Local warpings on monoclinal dip. (e) Accumulations on monoclines, due to thinning out or change in texture of the sand.
Page 639 - Paragenesis, a general term for the order of formation of associated minerals in time succession, one after another. To study the paragenesis is to trace out in a rock or vein the succession in which the minerals have deposited.
Page 578 - Robinson and Bridgeport lenses are portions of conspicuous sandy zones, belonging to the Pottsville. Mississippian. The Mississippian rocks underlie the Pennsylvanian and contain the most important oil sands. The upper portion, known as the Chester group, 1 is limited by erosion to the Tribune formation. Below the Chester in succession are the Ste. Genevieve and St. Louis formations. The Chester beds include the "Gas," Kirkwood, and Tracey sands, and the Ste.
Page 577 - ... it captive in its present position. The eastern side of the oil field also shows abundant water in the lower lens but apparently not so much as at the corresponding level on the steeper limb of the arch. Both water and oil are irregularly distributed on the east limb of the anticline. CONCLUSION. It is obvious from the position of the water and oil along the LaSalle anticline that the water has controlled the accumulation of oil in the arch. The water probably has been a means of originally collecting...
Page 576 - ... sand which is somewhat persistent over the area. Even this work loses much of its scientific value because parts of it are suppositional through the overlapping and wedging out of this sand bed, as well as those above and below it. The altitudes of the top lens are assembled and contoured in Plate 5. The general structure of the Robinson pool reveals a broad and gentle arch which is divided into two parts by a transverse basin. The northern part shows the arch to be about 6 miles wide with its...
Page 775 - CARPENTER, GEORGE W. On the Mineralogy of Chester County, with an account of some of the Minerals of Delaware, Maryland and other Localities.