# Practical Field Geology

McGraw-Hill Book Company, 1912 - 273 páginas

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Página v - Omer smote 'is bloomin' lyre, He'd 'eard men sing by land an' sea; An' what he thought 'e might require, 'E went an
Página 104 - C, and D and the plan-view will appear as shown. The line through B'v> C'v, etc., Fig. 2, is the edge-view or end-projection of the vein, and the dip is, of course, the angle included between this and the horizontal plane. The dip might also be found by passing a vertical projecting-plane through B perpendicular to the line of strike, and then revolving the line of intersection of this plane and the vein into the plane of the paper. This is the characteristic method of descriptive geometry, but when...
Página 116 - ... but the position of that from d, further in, shows that before the material could be filled out to the outer arc it would be over-running at d. "While the line EFG is the farthest limit to which the crest can be carried, it does not follow that the foot of the dump will run out to the property-line at all points. For instance, with the material falling away at an equal angle on all sides, it is evident that F cannot be pushed out far enough to cover the extreme corner without over-running on...
Página 116 - These arcs limit the position of the crest so far as a and a' are concerned. Similarly, for b and b' on the 900-ft. level, arcs swung with m'n' as a radius locate the crest so far as b and b' are concerned. Continuing this process for the intersection of each contour-line and the property-line, we obtain a series of arcs. The innermost arc, or the one towards the uphill side, limits the crest. Drawing a fair line tangent to the inside arcs, we have the crest EFG. An arc not used, such...
Página 121 - A FOLDED VEIN OR SEAM. Let Fig. 12 be a contour-map of an area on which an irregular outcrop has been partly located, as, for instance, at the stations marked with an X. At various other points, as 6, 9, 11, 19, drill-holes have been sunk and the seam located at the depths noted. The form of the folded seam may be determined if we can establish its contour-lines corresponding to those on the surface, and where these seam-contours intersect those of the surface of equal elevation we have points on...
Página 123 - ... which the seam lies. Elsewhere it has weathered away. The probable depth of the seam at any point may be obtained by subtracting the elevation of the seam from that of the surface, as indicated by the respective contours for that point. For instance, at G the depth is 690 ft. less 655 ft., or 35 feet. The value of this contour-method, where the outcrop is overgrown or obscured by soil, is obvious. An excellent example of its application will be found in the Masontown Folio of the US Geological...
Página 125 - FIG. 13. Fig. 13 illustrates how parallel strata may be used to corroborate and supplement direct data. This use of parallel strata has been described by MR Campbell '. The direct data of the upper section, Fig. 13, give only three points on the seam, which is everywhere obscured or eroded. If the intervals between I. and II. and II. and III. in the columnar section be established, and if I. and III. be located at various outcrops, as shown in the lower section, then the intervals may be set off...
Página 117 - To PLOT THE OUTCROP OF A VEIN, WHICH MAY BE CONSIDERED AS A PLANE SURFACE. Descriptive geometry methods may be used to determine the probable outcrop of a vein. First, let the vein be free from faults and foldings, and the strike and dip be known for some definite position, as A in Fig. 11. Draw an end-view looking up the strike-line. For convenience, let this end-view be drawn with the line XX through A perpendicular to the strike as the horizontal plane through A. Let the series of lines parallel...
Página 145 - Ore Deposits at the Contacts of Intrusive Rocks and Limestones, and their Significance as regards the General Formation of Veins...
Página 259 - Coal with Soda. — With its own volume of soda dissolves with effervescence to a clear bead. With more soda the bead is opaque. With Borax. — Clear and colorless. With S. Ph. — Insoluble. The test made upon a small fragment will usually show a translucent mass of undissolved matter of the shape of the original fragment. When not decomposed by S. Ph., dissolve in borax nearly to saturation, add S. Ph., and reheat for a moment. The bead will become milky or opaque white.