84 Prof. Sedgwick on the Carboniferous Chain 



The thickness from the bottom of the whole system to the top of the twelve- 

 fathom limestone is 1735 feet^ as determined by these numbers ; and from the 

 top of the great Scar limestone to the top of the twelve-fathom limestone, is 

 1135 feet. Btit a small correction must be made on account of dip; and a 

 more considerable correction on account of over-estimate, all the beds being 

 taken at the maximum thickness, which is never the case in any one section. 

 After all the deductions, there must remain a thickness of about 1000 feet for 

 the alternating beds between the top of the great Scar limestone and the top 

 of the twelve-fathom limestone; and as far as regards the mountains of Gars- 

 dale and Dent, 1 do not think that this is an over-estimate. It is, however, 

 right to state, that very few of the numbers in the preceding details are from 

 actual measurement. I wish them to be considered only as the average results 

 of a great many independent approximate observations. 



§ 3. Longitudinal section from Penigent to the plains of the Eden near 



Kirkhy Stephen, ^c. ^c* 



This section might have been extended many miles further towards the 

 south, through a region which, though of less elevation than the one here 

 described, has nearly the same external characters, and is composed of similar 

 groups of strata : but I wish to confine it to the part of the chain I have per- 

 sonally and repeatedly examined. 



Commencing at the top of Penigent, it passes just above the village of 

 Horton, and thence nearly in a straight line to the top of Ingleborough. The 

 summit of Penigent is, I believe, composed of beds subordinate to the second 

 millstone grit (Group 15.) ; and immediately below, the highest slope, Nos. 14. 

 13. 12, are finely exposed, and the coal bed of No. 14. has been worked in 

 horizontal drifts. Then comes a great limestone precipice representing 

 Nos. 11. 10. and 9. — No. 10. having nearly disappeared, and the twelve-fathom 

 and four -fathom limestones (Nos. ] 1. and 9.) making but one precipice. The 

 remaining part of the great escarpment is composed of No. 8. 



From the swallow holes at the base of No. 8. to the level of Horton Beck, 

 all the successive beds (No. 7. to No. 1.) may be traced without a single 

 omission. The black marble beds (No. 3.) have been quarried above Hull 

 Pot, but are not of good quality; and the group (No. 2.) is not more than 

 twenty or thirty feet thick f. The great Scar limestone is magnificently ex- 

 hibited ; and in it are Hull Pot and Hunt Pot. The former a great roofless 



* Plate VI. fig. 2. 



t Both in Ingleborough and Penigent the groups between the Scar limestone and the twelve' 

 fathom limestone, are of less aggregate thickness than in many other parts of the principal section. 



