broken clay, derived from its argillaceous shale beds, at the moment in which the Fracture and Dislocation took place; and hence have resulted those joints and separations, which, though they occasionally interrupt at inconvenient positions, and cut off suddenly the progress of the collier, and often shatter those portions of the strata that are in immediate contact with them, yet are in the main his greatest safeguard, and are indeed essential to his operations.[1]
The same Faults also, while they prevent the Water from flowing in excessive quantities in situations where it would be detrimental, are at the same time of the greatest service, in converting it to purposes of utility, by creating on the surface a series of Springs along the line of Fault, which often give notice of the Fracture that has taken place beneath. This important effect of Faults on the hydraulic machinery of the globe extends through the stratified rocks of every formation. (See Pl. 69. Fig. 2.) It
- ↑ "If a field of coal (says Mr. Budddle) abounding in water, was not intersected with slip Dikes, the working of it might be impracticable, as the whole body of water which it might contain would flow uninterruptedly into any opening which might be made into it; these Faults operate as Coffer Dams, and separate the field of coal into districts."—Letter from Mr. John Buddle, an eminent Engineer and experienced Coal Viewer at Newcastle, to Prof Buckland, Nov. 30, 1831.
In working a Coal Pit, the Miner studiously avoids coming near a Fault, knowing that if he should penetrate this natural barrier, the Water from the other side will often burst in, and inundate the works he is conducting on the dry side of it.
A shaft was begun about the year 1825 at Gosforth, near Newcastle, on the wet side of the 90 fathom Dike, and was so inundated with water that it was soon found necessary to abandon it. Another shaft was then begun on the dry side of the dike, only a few yards from the former, and in this they descended nearly 200 fathoms without any impediment from water.
Artificial dams are sometimes made in coal mines to perform the office of the natural barriers which Dikes and Faults supply. A dam of this kind was lately made near Manchester, by Mr. Hulton, to cut off water that descended from the upper region of porous strata, which dipped towards his excavations in a lower region of the same strata, the continuity of which was thus artificially interrupted.
