324 TYNEDALE ESCARPJlEKiTS ; 



impregnated with its particles. Take a homely illustration. Most 

 tourists may know that a shower falling upon cloth of loose tex- 

 ture is unpleasantly apt to soak along the fibre and gather at the 

 cuffs and borders. Let the tourist rough it a little, or, better 

 still, let him be a field- geologist, and his coat will not lack dust. 

 !N"ow, water straining along the meshes of a cloth is not unlike 

 water filtering through a felt of vegetable fibres. In both cases 

 it must pick up particles and drip off turbid. As for the coat 

 there is certainly no doubt about it ; every geologist is the sub- 

 ject of a hundred such experiments. 



One of the effects of vegetation, however, is to prevent the 

 shale from receding beneath, or undercutting , the escarpments. 

 Only when free from cover can it thus give way ; as it is a line 

 of rushes is usually the best mark of its position. 



5. The Whinsill. — This oft-times lofty ridge I take last, as 

 being an intruder among the more normal features. Intractable 

 to the quarryman, from the building of the Eoman "Wall until 

 quite of late years, the Whinsill might be supposed to defy also 

 the hand of time. But although generally the dominant feature, 

 its columnar jointing makes the dislodgement of its blocks easy, 

 and its ruin is generally great. Its talus below the Barrasford 

 Crag is no less than twenty feet thick measured at right angles 

 to its slope, and at other points. Crag Lough, for instance, the 

 rock has suffered probably to an equal extent. Granular disin- 

 tegration seems to be but slow. Coats of oxidized basalt, to which 

 I have been pointed by a farmer as clear demonstration of the 

 notion that stones grow, are generally found peeling away.*' But 

 even at the bottom of the talus I noted the fragments to remain 

 perfectly angular : and when the length of time during which 

 these deep-laid fragments have been exposed to disintegrating damp 

 is considered, it is evident from the mass of the talus that me- 

 chanical waste in the Whinsill enormously exceeds the chemical. 



* William Hutton, in his almost ingeniously erroneous paper on the Whinsill, takes 

 occasion to point a moral against the Huttonian school fi-om the unweathered appearance 

 of the huge whin blocks lifted out by the Romans from their fosse at Limestone Bank. 

 George Tate of Alnwick, who has a word of admiration, and a diagram, for the Sewing- 

 shields and neighbouring crags, remarks this peeling skin, evidently with a quiet caveat 



