348 Mr. Horner on the Geology of the 



colour, apparently derived from chlorite, with purplish stains 

 .and including small spherical masses of a white earthy tex- 

 ture, which give to the mass an amygdaloidal structure : it may 

 .be considered as a variety of argillaceous slate, and as it occurs 

 in strata conformable with the usual varieties of the grauwacke 

 formation, it belongs I have no doubt to the same class : it is 

 found to be very useful as a fire stone. The other place where 

 I found a slate very similar to this was in the neighbourhood of 

 Cheddon Fitz-Paine. 



§ 10. In passing through the village just named, I observed In 

 the street a small block of stone differing in appearance from any 

 I had found previously, and upon examination I found it to be 

 granite, a rock I had searched for before without success, and in- 

 deed this is the only place where I saw an unstratified rock in the 

 whole district, the porphyry and greenstone which accompany the 

 grauwacke formation in Devonshire being wholly wanting here. 

 On inquiry I found that this granite, called by the country people 

 Fettle Stone, came from an old quarry not far distant in the grounds 

 of Hestercombe, belonging to T. Warre, Esq. My informer 

 brought out of his house a whetstone which he said came from 

 another quarry close by the Pottle Stone. It was a greenish com- 

 pact stone, very like some hornstones or some of those close- 

 grained siliceo-argillaceous compounds which it is very difficult to 

 name. On going to the quarry, which is almost entirely over- 

 grown with brushwood, I found the granite in situ : it is small 

 grained, and consists of dull flesh-coloured felspar, with green 

 mica, and a small quantity of quartz. It occurs in the lower part 

 of the hill and occupies a very limited extent. Immediately ad- 

 joining is the spot where the whetstones are got. Here I found 

 regular strata of slate similar to that occurring in many parts of 



