from Penigent to Kirkbj/ Stephen. 71 



Like the Peak limestone, the group, here described, is full of fissures and 

 clefts (often of unknown depth), in which the mountain torrents are engulfed ; 

 and, after running in subterranean channels, and uniting with the waters of 

 other sources, emerge in copious streams in the lower regions of the neigh- 

 bouring valle)'s. But of all the phfenomena connected with the drainage of the 

 waters through the scar limestone, the beautiful reciprocating well above 

 Giggleswick is the most remarkable, and even to this may be found a counter- 

 part among the limestone hills of Derbyshire. 



It contains, like the limestone of the Peak, many caverns of consider- 

 able extent ; some partly open to the surface, others only to be approached 

 through a narrow horizontal entrance. In some of these great subterranean 

 recesses we find waterfalls of no common grandeur; in others we see no 

 waters, but we hear them roaring among the inaccessible chambers of the 

 rock. As a general rule, these caverns have perpendicular walls, and often 

 nearly flat roofs. However greatly modified, they have, therefore, not been 

 formed by the mere long-continued erosion of the waters passing through 

 them. When the conformation is such as I have pointed out, the opposite 

 walls are portions of the same stratum, and the flat roof is composed of the 

 superincumbent stratum ; and the cavern has the exact appearance of having 

 been formed by one of the beds sliding off horizontally from the side of a ver- 

 tical joint. I do not think such a movement impossible. The component 

 strata, when first lifted up, were perhaps in a very unequal state of solidifica- 

 tion, so that one part would offer a greater resistance in any given direction 

 than another. The points of greatest stress might also be very unequally dif- 

 fused ; and, in consequence, the strata may have started among themselves, 

 and undergone considerable relative movements, not unlike those we may 

 observe among the timbers of a ship which has been wrecked, and thrown 

 violently on her beam ends. In this way some caverns may have been formed 

 by the sliding of solid beds upon each other, some by the gradual removal of 

 incoherent or imperfectly solidified portions of the rock, and others by both 

 causes combined. The subject is one of considerable difficulty, and I wish to 

 exclude no agent from its proper share in producing the existing appearances. 

 AH I contend for is, that in such cases as I have afluded to, the slow erosion 

 of the waters flowing through the interior chambers of the scar limestone is 

 not the kind of action by which its great caverns have been scooped out. 



The mineral characters of the scar limestone are too well known to be 

 detailed at any length. The great bottom shales found in so many parts of 

 England are almost entirely wanting in the line of section, and in the neigh- 

 bouring country. Perhaps they are represented, in a very obscure form, by 

 some dark-coloured beds of impure limestone, separated by bands of shale. 



