BY HUGH MILLEK. 



307 



WATERFALL 



feet of shale below it, is fifty- six feet. 

 A hundred and ninety feet further 

 down stream, the gorge's width has 

 increased to ninety-two feet. Its 

 walls thus stand thirty-six feet fur- 

 ther apart, so that while the water- 

 fall, employing its more powerful 

 tools of erosion, has been cutting- 

 back a hundred and ninety feet, the 

 quiet action of the atmosphere has 

 removed eighteen feet of sandstone 

 from each side. This is a considera- 

 ble ratio, nearly one-tenth. A much 

 smaller ratio to the erosion that has 

 dug out our valley systems should be 

 Woodcut No, 4.— Diagram of capable of working large effects upon 



gorge in Dinley Burn, shemng en- ii i • ij. p i ja 



, ^ ' .. . the heights of a country.* 



largement by atmospheric disinte- ^ "^ 



gration. The fate of masses severed from 



the parent rock naturally is to moulder away grain by grain. 

 A lesson of gradual waste may be learnt from a monolith standing 

 in the grounds of Swinburn Castle. This stone, a shaft about 

 eleven feet high, is a portion of a stratum of compact, fine- 

 grained sandstone stripped from its outcrop and raised endlong. 

 In its original position it would be exposed along one of its flatter 

 sides, but since its erection waste has attacked its summit, and 

 its point now resembles an Alpine peak in miniature. It is 

 sharp and attenuated atop, and rugged flutings descend upon its 

 sides, their direction determined by the slant of the stone. 



* When the above was first written this instance was supplemented by two others 

 taken from tlie Upper and Middle Falls of the well-known Hareshaw Linn, near Belling- 

 ham. I have since then remarked suflicient curvature in these gorges to make the stream 

 probably scoop out one side. In a case adduced by Mr. Goodchild (loc. cit.) the ratio is 

 only as forty to one and a half, i.e., only one-twenty-seventh. This ho states to be an 

 "extreme case," but, in view of the immense effects produced by stream action, even 

 this is significant. It must be remembered that the stream not only attacks with better 

 applied force than the atmosphere, but in many cases has less and less to do as the fall 

 recedes. Thus, In the Dinley Burn, Instead of having eight or ten foot of saiulstone to cut 

 back through, as at lirst, the trenching of the stream above the fall has left only about 

 two. 



