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vable pillars, has cleft their tops and furrowed their sides, in the lines 

 of quickest descent, without regard to the irregularities of their com- 

 position. One of the stones leans remarkably and threatens to fall; 

 but an examination of the rain channels shows the inclination of the 

 stone to be of most ancient date, for these descend further on the 

 upper sloping face than on the under. 



Stones which have fallen from the limestone cliffs of Switzerland 

 have been furrowed by the rain since the time of their descent. 



On Doward Hill near Monmouth, and still more in the broad sur- 

 face of the crags around Ingleborough in Yorkshire, the effects of the 

 rain on the weathered beds of limestone are evident and remarkable. 

 But the most striking phenomena of the kind known to the author 

 occur on Hutton roof crags near Kirby Lonsdale. 



Hutton Roof Crags afford an opportunity of tracing the rain chan- 

 nels over an immense surface of bare limestone rocks, lying nearly 

 level on the hill- top, but sloping rapidly down the sides to the east 

 and south. On the level top of the hill the stones are variously 

 worn in hollows and grooves, irregularly united and running in dif- 

 ferent directions, according to little inequalities of the ground ; but 

 on the steep slopes the channels are extended into long furrows, 

 which, meeting at acute angles, enlarge, widen, and descend the 

 hill-side in lines following exactly the declination of the rocks, and 

 stopped only by the few and distant fissures, beyond which other 

 systems of concurrent grooves begin. 



