ranging E.S.E. between the Rivers Lune and IVharJe. 13 



tain ; but on approaching- the valley of Wharfe they are found covered by the 

 northern limestone, whose lower beds are filled with pebbles of slate, the 

 largest lying- at the bottom. 



At this place I observed a very interesting occurrence of large slate blocks 

 scattered as well on the higher limestone scars of the north, as on the lower 

 ranges of the same rock on the south. We see the slate in situ covered by the 

 limestone edge, on the top of which, 50 to 100 feet above, we find the hu«-e 

 transported blocks of slate in great abundance ; further on the scars, to an 

 elevation of 150 feet, the blocks are still numerous, and they may be seen by 

 ascending one ledge after another almost to the top of the Fell, 500 feet above 

 their original position. They appear to have been driven up at a particular 

 place by a current toward the north, and afterwards carried along the surface 

 of limestone in a narrow track toward the summit of the Fell. The contrast 

 is very interesting between these rough angular masses of slate, and the 

 smoothed rain and time-worn limestone which supports them. 



Valley of IVharfe. 



The northern branch of the valley of Wharfe expands in its upper part into 

 a wide dale based on slate rocks, and encircled by high scars of limestone. 

 These are in several places undulated, so that the slate is exhibited at very 

 different heights on the opposite sides of the valley. In front, at the upper 

 extremity, the granular variety of slate rises to the height of 100 feet; at the 

 same height it appears on the east side, but is nearly level with the base of the 

 valley on the west. Lower down, where the opposite scars are more level, 

 slate fills the whole wide valley, ascends both hill-sides, and is seen touching 

 the limestone in several fine natural sections. One of these on the eastern 

 side*, not easily reached over a slope of loose stones 100 feet high, exhibits 

 the slate in distinct laminae of cleavage directed E.S.E. and dipping 45° S.S.W. 

 Pretty regular joints cross it with a dip N. 70°. It is cut off by a level top, 

 on which rest beds of limestone, filled, for about 8 or 10 feet, with very large 

 boulders of slate crossed by the same fissures which divide the calcareous paste. 

 In one of these pebbly beds I found a noble mass of Astreea lithostrotion. 



Rihhlesdale. (See Section F, Plate I.) 



The slate rocks are seen ranging with -a level top under the precipices of 

 Moughton Fell, till, beyond the village of Horton, the limestone descending to 

 the river marks their northern boundary. Their southern range is on a lower 

 level, under the calcareous summits of Feizer to the Ribble near Little Stain- 



* See Section E, Plate I. 



