^^^' 55'] ^^^ CEAVEN" DISTRICT OE YORKSHIEE. 331 



III. N'aTURE of the DlSTUEBANCES SOTJTH OF THE CRAVE^^ FaULTS. 



One of the most suggestive features in connexion with limestone- 

 knolls is their occurrence in districts where the rocks have been 

 affected by profound earth-movements, so that they present phe- 

 nomena analogous to those described by Heim and other writers on 

 the highly disturbed sedimentary rocks of Alpine regions. This is 

 true not only of the knolls of the Craven district, but also of those 

 of all other areas which I have examined, or concerning which I 

 have read, as will be seen in the sequel. The number of cases 

 where knoll-structure is found in disturbed regions of this character, 

 and the fact that no knolls have been discovered in areas where the 

 rocks have not undergone intense plication and fracture, is sufficient 

 to show that this is no mere coincidence, but that the existence of 

 the knolls has some definite connexion with the disturbed character 

 of the rocks. 



Although the existence of marked plications affecting the rocks 

 south of the Craven Fault has long been recognized (the sharp folds 

 of Draughton Quarry, near Skipton, have become classic), the very 

 great disturbance of the rocks does not seem to have been fully 

 appreciated, chiefly because signs of such disturbance (as is now 

 well known) are at a cursory glance less obvious than when the rocks 

 have been less disturbed, for in the latter case the middle limbs of 

 the folds are intact, and the fold can be seen ; whereas in the former, 

 the middle limbs being destroyed and replaced by faults, there is a 

 general parallelism of the strata which would lead anyone taking 

 a cursory view to suppose that rocks which are really sharply bent 

 and repeated form portion of one gentle fold. 



I propose, therefore, to bring forward evidence of the intense 

 nature of the movements which the South Craven Lower Car- 

 boniferous rocks have undergone. Beginning with the Draughton 

 Quarry itself, one finds much more disturbance in the rocks at the 

 north end of the oft-figured eastern face than in the rest of the 

 quarry. An inspection of the accompanying figure (fig. 1, p. 332) 

 will show this. I would also refer those who are acquainted with 

 the structure of a district wherein the strata have been much affected 

 by lateral pressure to examine figs. 1 (p. 15), 2 (p. 18), 4 (p. 24), 8 

 (p. 35), 9 (p. 38), and 11 (p. 39) in the Geol. Surv. Mem. on 'The 

 Geology of the Burnley Coalfield,' 1875, as samples of the appear- 

 ance of the strata. Fig. 4, the section in the railway-cutting near 

 Eibchester Station, is especially suggestive. A beautiful section 

 showing similar structure is visible in the Hambleton Rock Quarry, 

 close to Bolton Abbey Station. Examples might be multiplied, for 

 the district abounds with them, but these will suffice to show the 

 nature of the folding which the rocks have undergone, and will, I 

 think, convince anyone conversant with such structures that we are 

 here dealing with a district which has been subjected to great lateral 

 pressure. 



Examination of these sections, suggestive as it is, is only a 

 preparation for the information obtainable from detailed study of 

 the rock-masses, and I proceed to give some account of these 



