of a kind of terra lapidosa, or hardened clay, as soon 

 as they were exposed to the rains and frost they 

 mouldered away. These seemed as if they were of 

 very recent production. In the chalk-pit, at the 

 north-west end of the Hanger, large nautili are some- 

 times observed. 



In the very thickest strata of our freestone, and 

 at considerable depths, well-diggers often hnd large 

 scallops or pectines, having both shells deeply stri- 

 ated, and rido:ed and furrowed alternatelv. Thev 

 are highly impregnated with, if not wholly com- 

 posed of, the stone of the quarry. 



LETTER IV. 

 To Thomas Pennant, Esq. 



As in a former letter the freestone of this place 

 has been only mentioned incidentally, I shall here 

 become more particular. This stone is in great re- 

 quest for hearthstones and the beds of ovens; and in 

 lining of lime-kilns it turns to good account ; for the 

 workmen use sandy loam instead of mortar ; the sand 

 of which fluxes, and runs by the intense heat, and so 

 cases over the whole face of the kiln with a strong 

 vitrified coat like glass, that it is well preserved from 

 injuries of weather, and endures thirty or forty 3'ears. 



When chiselled smooth, it makes elegant fronts for 



II 



