XXIII.—On the Great Fault called the Horse in the Forest of Dean Coal-Field.

The great fault in the Forest of Dean, called “ the Horse,” ranges in the direction of S. 31° E. by compass, in the Coleford High Delf seam of coal. The term Fault is used here in conformity with the usual mining phraseology, which assigns that term to any interruption in the regular deposition of the seam, or vein of coal. The Horse, however, is not what geologists term a fault, as there is no accompanying dislocation of the strata. The coal is deteriorated in quality in some places, in others it is considerably thinner than the average height of the seam or vein, and in the principal part of the Horse it is altogether wanting. (See accompanying Section, woodcut, fig. 1.) It may also be observed, that the miners in Dean Forest apply the term vein to a stratum of coal, while this term in the north of England is applied to mineral veins only; and many similar instances exist in mining districts where local terms convey an erroneous impression, either as compared with the terms used in other places or with the scientific language of Geology. That portion more particularly called the Horse has been traced by the workings on each side of it in Coleford High Delf seam about two miles, and its breadth varies as shown on the accompanying plan, from 170 to 340 yards. (See woodcut, fig. 2.) The only drift or tunnel which has been carried through it, in a transverse direction, passes under