Joseph Beete Jukes

“ One often sees a mere straight line representing a fault on a geological map, and sometimes is tempted to wonder what becomes of it, or how any mass of beds can be elevated or depressed in consequence of a single crack running through them. That such single-lined fractures do occur, however, the beds on one side bending down, while those on the other have remained stationary, or are perhaps bulged upwards, is proved by the occurrence of the east and west faults, before described, traversing the South Staffordshire coal-field. ”

“ 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." ”

“ At all events, it is clear from our previous descriptions, and from an inspection of the maps and sections, that before the production of the dislocations of the great boundary faults, the New red sandstone spread over the coal-field and whole district of South Staffordshire, and we can see no reason why it should not have had the whole of its beds everywhere, or why these beds should not have been everywhere covered by the Lias. ”

“ 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 ”

“ 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. ”

“ Or if we continue the crack to the edge of the plank, which we may look on as a great boundary fault, we may bend one side so as to make the dislocation gradually increase from its commencement up to its termination. Of the latter case we have examples in the Corbyn's Hall and Brockmoor faults, that gradually increase their "throw" as they approach the western boundary fault. ”

“ In the matter of faults and dislocations in the Coal-measures especially, there are many curious observations yet to be made, and many cases occur that would at first puzzle a geologist, and might be deemed by him impossibilities till he saw them before bis eyes. ”

“ Scale, 1 inch equal to 20 feet The triangular gap A in the Thick coal is filled up by a corresponding portion of the beds above the coal, consisting of shale and clunch, the lower part of which contains several courses of nodular ironstone, marked 1 in the figure. The strata in A are said to be "much broken and contorted, especially towards the apex. The ends of the strata are turned a little upwards. Two pieces of bituminous shale (2) are found on one side of it, which should under ordinary circumstances occupy the top of the coal." ”

“ He, knowing that true faults when found in one bed must necessarily affect all the beds above it up to the surface, and looking at this gap in the Thick coal as a fault, expected to meet a similar gap in the Brooch coal above. ”

“ It follows from the above considerations, that if there be only one or only two lines of fracture they must gradually diminish and end somewhere, and that the dislocated ground must have at least one place of maximum disturbance towards which it bends down either in one or several directions. ”

“ Among other things we may easily imagine the apex of the wedge to suffer considerably in some places, and to be ground off till it may have a blunt base, not only of 8 feet, but of many yards in width. ”