Page:The South Staffordshire Coalfield - Joseph Beete Jukes - 1859.djvu/210

192 of "fault" can be assigned a definite technical meaning, it is plain that their insertion into legal documents, agreements, &c., can only be the fruitful cause of error and dispute, leading to much useless expense, and possibly to much necdless ill feeling.

The remedy for the correction of error both in practical operations and in legal agreements, depending on the proper understanding of the nature of faults, is obvious. It is that the ground bailiffs, mine agents, and surveyors, the men on whose word and authority these things mainly depend, should have the opportunity of acquiring larger and more accurate knowledge, and more correct ideas, as to the rea] nature of the matters they are engaged with. A comparatively slight acquaintance with the rudiments of practical and theoretical geology, such as might be acquired by any intelligent person from a few months' instruction from a competent teacher, would be sufficient to produce a perfect uniformity in all such men's Opinions as to what was and what was not "a fault." Such instruction would enable every mine agent in future life to observe accurately, and to arrange and record his observations truly and methodically, so that all his subsequent experience would be applied in the right direction, instead of, as is too often the case, in the wrong one, and tend to increase his real knowledge, not to add to his misconceptions.

The South Staffordshire coal-field has been so thoroughly worked and explored, that a study of its faults and dislocations will add something of precision and completeness even to the knowledge of a professed geologist.

It is clear that a single fault, that is a fissure running along one straight or slightly curved line, can only produce a "throw" or dislocation of the beds along a part of its course. There must be a point in the fissure where the dislocation begins, from which it increases to a maximum, and another point where it gradually ends, and it is scarcely possible that the mere fissure will terminate at either of those points. Such a fault may be likened to a crack in a deal board which ends in the board each way before it reaches its extremity. It is evident that we can only elevate or depress a portion of the board on one side of the crack above or below the corresponding portion on the other side by pushing it in or near the centre of the crack, and causing that portion to bulge. The protuberance of the bulge will be greatest at this part, and gradually diminish each way to the points, where, though the crack may continue, the parts on opposite sides of it retain their relative position. Such "single-lined faults" are those that extend east and west across the part of the coal-field between Dudley and Bilston. Although single in the centre of their course, they often split into one or two small branches near their extremities. The dislocation may be increased by the measures on one side of the fault being bent up into a bulge along its course, while those on the other are bent down. We may, moreover, conceive it possible for the beds ranging along the fault to have more than one "bend" in them, and thus the amount of the throw to diminish and again increase; and if the beds on