126 



HARDWICKE'S SCIENCE-GOSSIP. 



slate weathers away ia" small '[pieces and Hakes. 

 All those too who have gone from Keswick to 

 Buttermere by Honister Pass, returning by New- 

 laud's Vale, will have contrasted the rugged cliffy 

 mountain-sides of Borrowdale with the smooth 

 green sloping hill-sides seen ou ascending the New- 

 land's Pass (fig. 7S). 



I''ig. 78. View on ascending' the Newiand's Pass iruin 

 Buttermere. 



Although smoothness of outline is the general 

 character of the Skiddaw slate mountains, yet do 

 we find occasional exceptions to this, arising from 

 special circumstances. Thus, when the slate con- 

 tains harder sandy beds, these stand out more or 

 less iu relief and give rise to bolder cliff-like parts. 

 Again, the masses of eruptive greenstone frequent 

 among the Skiddaw slate series, also often modify 

 the otherwise smooth scenery ; on the east side of 

 Hindscarth is a long patch of greenstone which 

 forms a very craggy side to the mountain, this rock 

 being harder than the slate and falling away in 

 blocks. 



The relative direction and amount of the true 

 dip and .the cleavage dip of the slate frequently 

 affects the form of the mountain. To this'is due, 

 in great measure I believe, the shape of Blencathra 

 (Saddleback) ; the gentle slope to the north, at the 

 back of the mountain, corresponding in direction 

 and inclination with the bedding dip, and the fine 

 ravines upon 1 he south-east side being produced by 

 the weatheiiug along the steeper cleavage dip. 

 One flank of the southern part of Hindscarth 

 corresponds with the strike of the cleavage-planes 

 of the slate, and a sleep glacis is consequently 

 formed at an angle of about 50", corresponding to 

 the dip of the cleavage. Close to this also, between 

 Hindscarth and Dale Head, a stream has cut out a 

 very deep narrow ravine along the line of the 

 cleavage. Many of the narrow edges often found 

 to unite mountain with mountain or to run off from 

 a main ridge, are in great part formed by the easy 

 weathering of the slate along the cleavage-plaues. 



If now we glance at the rocks of the volcanic 

 series, we find among the mountains of Borrowdale 

 all the variety of rugged and craggy aspect due to 

 hard rocks, but yet rocks of various degrees of 

 hardness. When standing on Stye Head Pass one 



can see at once the connection between the grandly 

 rude step-like form of the Scawfell range, and the 

 inclination of the massive stratified beds of altered 

 ash forming it, dipping at an angle of 25° in a S.S.E. 

 direction, and traversed by numerous joints and 

 dykes more or less at right angles. 



Where there occurs a great thickness of ash of 

 nearly uniform hardness and well cleaved, the form 

 of ground oftentimes more nearly approaches that 

 of the Skiddaw slates ; thus, along part of the 

 summit of the Helvellyn range is such a thickness 

 of ash much cleaved, and the form is rather that of 

 Blencathra in both its phases. 



The Vale of St. John is a striking instance of the 

 dependence of mountain-form upon geological 

 structure. Standing at its lower end and looking 

 up the valley, there is seen on the left a long range 

 of precipitous mountains with evident lines of 

 bedding running along its face, the strata of hard- 

 ened ash dipping steadily into the hill-side at from 

 8° to 30°; while on the right the hill is made up of 

 alterations of hard beds of trap and softer ash lying 

 in a long synclinal trough faulted at several points, 

 each hard bed forming a prominent terrace on the 

 liill-side, at first dipping south at about 35°, then 

 flattening out above Sosgill, and afterwards dipping 

 north at a low angle above Low Bridgend. 



The various faults that run through this district 

 tend often to produce marked effects upon the 

 scenery ; not that the actual dislocation has given 

 rise, upon the ground, as we now see it, to gaping 

 fissures or long precipitous walls of rock, but that 

 rocks of various degrees of hardness having been 

 thrown together along the line of fault, the denuding 

 powers liave acted unequally upon them, giving 

 rise to well-marked features. The peculiar wedge- 

 shaped form of Honister, as seen from Buttermere, 

 is due in great part to faults meeting at an obtuse 

 angle and throwing the comparatively soft Skiddaw 

 slates against the hard traps and ashes of the 

 Borrowdale volcanic series, the latter forming the 

 steep craggy upper parts, and the former the more 

 sloping and grassy ground towards the base of the 

 great wedge. 



Lines of fault are often found to run through 

 mountain gaps or passes, unequal weathering having 

 taken place along such lines. Such cases may be 

 well seen on High Rigg, between St. John's Vale 

 and the Naddle Valley, where advantage has been 

 taken of these long breaks in the small rocky 

 escarpments to build straight stone walls, so that 

 the fault and the wall very often nearly coincide. 



Before closing this subject 1 wish to call attention 

 to the very great number of wholly or partly fiUed- 

 up lakes scattered over the district. L'pon the 

 fell-tops one constantly meets with tarns now con- 

 verted into peat-mosses or filled up by stream-borne 

 detritus. In the main valleys old lake-beds are also 

 numerous, and every existing lake is partly filled 



