Mr. Lhwyd to Mr. Ray. 25? 



fietit thereto, which I have obferv'd in the Mountains 

 of Caernarvon/hire^ viz. 



i. Firft, That generally the higher the Hills are, 

 the more fteep are their Precipices and Declivities, 

 (I except the Sea Rocks) thus Moel y Wydhrha, y 

 Grib gvtcb, and twenty others that might be named, 

 reputed the higheft Hills in Wales , have the fteepefi: 

 Rocks of any Mountains I have feen % and that not 

 only in their higheft Cliffs, but alfo in moft of their 

 other Crags, till you defcend to the lower Valleys: 

 This I can afcribe to nothing elfe but the Rains and 

 Snow which fall on thofe great Mountains, I think, 

 in ten times the Quantity they do on the lower Hills 

 and Valleys. f. 



z. I have obferv'd a confiderable Quantity of the 

 Chips or Parings ( if I may fo call them ) of thefe 

 Cliffs to lie in vaft Heaps at the Roots of them ; and 

 thefe are of feveral Sorts and Materials > being in fome 

 Places cover'd with Grafs, and in others as bare as the 

 Sea Shore : And thofe bare Places do confift fome- 

 times of Gravel, and an innumerable Number of 

 Rock Fragments, from a Pound Weight to twenty, 

 &c. and are fometimes compofed of huge Stones, 

 from an hundred Pound Weight to feveral Tuns. 



3. In the Valleys of Lhanberys and Nant-Phrancon^ 

 the People find it neceffary to rid their Grounds of- 

 ten of the Stones which the Mountain Floods bring 

 down 3 and yet notwithftanding this Care, they of- 

 ten lofe confiderable Parcels of Land. 



4. I affirm, That by this means not only fuch 

 Mountains, as confift of much Earth and fmall Stones, 

 or of fofter Rocks, and fuch as are more eafily diflb- 

 luble, are thus wafted , but alfo the hardeft Rocks 

 in Wales * and they feem to be as weighty, and of 

 as firm and clofe a Texture as Marble it felf. It 

 happen'd in the Valley of Nant-Fhrancon, Anno i68f. 

 that Part of a Rock of one of the impendent Cliffs, 

 cali'd jr Hyfiae, became fo undermined ( doubtlefs. 



hf 



