TRANSACTIONS OP SECTION C. 399 



defined part between the two great gaps — the Tyne Gap and the Craven or 

 Aire Gap. In this part of the Pennines the mountain masses are broader and 

 higher, and the structure is somewhat different from that of the Pennines south 

 of the Craven Gap. The familiar anticline is not so conspicuously developed 

 as in the southern half of the Pennines. 



In the Northern Pennines the student may see very clearly indeed the 

 broad dependence of the topography upon rock-character, rock-position, and 

 geological history. 



The Craven or Aire Gap may be taken as a convenient starting-point. This 

 is a lowland region of roughly triangular form drained by four local river 

 systems : the Wharfe, the Aire with Broughton Beck, the Ribble with the 

 Lancashire Calder, and the Wenning (one of the feeders of the Lune). Each 

 of these outlets of the ' gap ' is utilised by a railway. The Leeds and Liverpool 

 Canal follows the valleys of the Lancashire Calder and the Aire, and crosses the 

 Pennines at an elevation of a little over 500 feet (the highest point is at Foul- 

 bridge Tunnel, near Colne). 



The Middle Pennine Gap is determined by the great Craven Fault system 

 and the folding of the strata to the South and South- West of the fault. The 

 general direction of the folding is from W.S.W. to E.N.E. Near the Fault 

 there is considerable and somewhat intense local folding, and probably some 

 repetition of the beds. 



North of the Craven Gap — and stretching to the Tyne Gap — is the Plateau- 

 or Block-country — the Northern Pennines of this paper — determined mainly by 

 the three gyeat western fault systems ; these are the Pennine, the Dent, and 

 the Craven Faults. Three ' blocks ' of the Northern Pennines are thus formed : 

 (1) the Cross Fell block, (2) the Mallerstang or Dent block, (3) the Ingleborough- 

 Penygent block. On these plateau-blocks the mountains stand, excellent 

 examples of mountains of circumdenudation or residual mountains. Ingle- 

 borough or Penygent may be taken as a type of these mountain masses, standing 

 on the plateau-Hoor of the Great Scar Limestone and capped by outliers of 

 Millstone Grit. The Great Scar Limestone is gradually replaced tovyards the 

 north by the coming in of the Bernician type. The Great Scar Limestone of 

 the Penygent block is a region famous for pot-hole« and underground streams, 

 such pot-holes as Gaping Ghyll and Alum Pot being well known. On the great 

 plateau numerous streams disappear to reissue in the valleys below, frequently 

 at the unconformity where the limestone, with or without its basement con- 

 glomerate, lies almost horizontally on the upturned edges of the Older Palaeozoic 

 rocks. 



These plateau-blocks are not all similarly related to the adjacent westerly 

 regions. On the east of the great Peimine Fault is the wedge-shaped Vale of 

 Eden, filled with Permian and Triassic strata. There is an interesting inlier 

 chiefly of Older Palaeozoic rocks occurring between the Carboniferous plateau- 

 block and the New Red beds of the plain. This is known as the Cross Fell 

 inlier, and is characterised by a series of magnificent ' pikes,' like a narrow strip 

 of the Lake Country tacked on to the western edge of the Pennines. This 

 inlier stretches from near Brough in the south to Melmerby in the north. The 

 Dent Fault has its downthi-ow to the east, and along the complex fault-line 

 the Carboniferous Limestone is in "contact with the Older Paleozoic rocks of the 

 Howgill Fells and the moors to the north and north-east of Kirkby Lonsdale. 

 The Carboniferous block to the east of this fault is the Mallerstang block of 

 this paper. It is remarkable for the great number of mountain masses which 

 rise to between 2,000 and 2,400 feet. An eastern part of this block is the 

 original region of the Yoredale of Professor Phillips (Wensleydale is Yoredale or 

 Uredale). The Craven Fault system throws the Carboniferous Limestone, 

 chiefly the Great Scar Limestone, against Permian, or Coal-measures, or Mill- 

 stone Grit, or the higher divisions of the Carboniferous Limestone itself. 



To the geographer the change of scenery in crossing these faults is most 

 interesting. The view from the western limestone scars of the Cross Fell block 

 across the Vale of Eden to the Lake District mountains is one of the finest in 

 Britain. The change from the Older PaUeozoic Howgill Fells, Grayrigg Fells, 

 Middleton and Barbon Fells eastward across Garsdale or Dentdale to the Car- 

 boniferous Fells of the Yoredale country of Mallerstang is, perhaps, not so 



