68 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 5, 



closed the web seems to have been folded in between them. These 

 prints may be attributed to some Batrachian animal, or possibly to 

 the Rhynchosaurus of Prof. Owen, and they resemble the set figured 

 by Sir R. Murchison and Mr. Strickland in the Geological Trans- 

 actions*. These latter were however from the new red sandstone 

 of Shrewley Common, Warwickshire, and exhibited a tail impression 

 referred to the animal of the footprints. 



2. On the circumstances and phcenomena presented by the Granite 

 of LuNDY Island, and of Hestercombe in the Quantock 

 Hills, compared with those which characterise the Granites of 

 Devon and Cornwall. By the Rev. D. Williams, F.G.S. 



The author commenced by referring to two former papers read be- 

 fore the Society f, in which he pointed out the condition of moun- 

 tain limestone and new red sandstone at their contact with trap- 

 rocks, and expressed his opinion that the trap was itself in great 

 measure or entirely an altered condition of the rock which it seems 

 to penetrate. He now states that he has found very numerous in- 

 stances of similar reciprocal effects or mutual metamorphism in 

 Devonshire and Cornwall, whenever the sedimentary strata are in- 

 tersected by dykes of igneous rock, or contain it in an imbedded 

 form, but that very different effects are observable when these strata 

 have been invaded by so-called granite veins or vein-like processes. 

 He proposes therefore to select two instances in confirmation of the 

 evidence formerly adduced, and he wishes these two to be taken 

 merely as examples. He considers the hypothesis of injection in- 

 sufficient to account for the phaenomena presented by the amygda- 

 loidal traps and their association with the new red sandstone in the 

 quarries about Exeter, Crediton and Tiverton. 



The granite or syenite of Hestercombe in the Quantocks was 

 first described, many years ago, by Mr. L. Horner J. It is a true 

 dyke extending at first for about a quarter of a mile in a direction 

 north-east by east and south-west by west, cutting the slate-rocks 

 obliquely. It may then be traced by the rubbly tillage land above 

 in a direction due west, as far as a little glen and rivulet about a 

 furlong and a half distant, where it occurs at the northern extremity 

 of an old and extensively worked slate-quarry, its hard refractory 

 nature having stopped the excavation in that direction. It there 

 dips S.S.W. at an angle of about 40°. At the eastward quarry, 

 where it is vertical, the slate, which abuts immediately against it, is 

 thickly traversed by small veins of quartz, mica and oxide of iron, 

 which give it a brecciated aspect, and the adjacent slate is highly 

 indurated, yielding a stone useful for making hones. In this case the 

 slate is altered to a distance of about a foot from the dyke, and the 



* 2n(l Ser. vol. v. pi. 28. 



t Vide Quart. Geol. Joui-n. vol. i. p. 47 and p. 148. 



X Geol. Trans., 1st Series, vol. iii. p. 338. 



