Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/411

 Rh 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.

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