Transactions of the American Institute of Mining, Metallurgical and Petroleum Engineers Volume 21
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 edition. Excerpt: ...the displaced extension of the vein must be sought for at the place opened. The directions which may then be found useful are set forth below as rules, together with the principles which underlie them. To save unnecessary repetition, the term "vein," as used below, may be understood to include all forms of tabular deposit. Rule I.--Follow the trail of the vein, For instance, the fault is filled with angular fragments broken from the walls, usually lying in a clay matrix. If the motion were slow and took place under pressure without much clear opening, the debris of the vein should occupy that portion of the fault lying between the ends of the veins and that portion only (Fig. 2). This indication, however, is sometimes confused by a secondary deposit of mineral or a similar original deposit in the fault-crevice. Rule II.--Follow the bending of the vein at the fault. Many rocks are slightly, plastic and show evidences of bending before fracturing (Fig. 3); and, during the grinding incident to the formation of the fault, a still sharper "drag" or wedging-out may take place at the fault (Fig. 4). In both cases, the bending must necessarily take place in the direction of the throw of the fault. If, however, a subsequent horizontal compression arise, the vein may be curled in a reverse direction (Fig. 5); but this is rare. The indications to which Rules I. and II. can be applied may be very slight or entirely absent. The restoration of ground disturbed by a multiple or step-fault usually develops a gentle monocline, the dip of the vein in the various blocks remaining nearly the same as that part of the monocline which they occupied just before the fracture. This probability may give some intimation of the dip of the vein on...
- 189 x 246 x 21mm | 699g
- 13 Sep 2013
- United States
- black & white illustrations