528 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



I have already shown that the interesting fauna of Brocastle 

 is derived from a thin band of conglomerate resting immediately 

 upon the Carboniferous Limestone, and that, wherever smj fissure 

 in the limestone occurred, a Liassic fauna, as was also the case in 

 the Mendip Hills, occupied it. The same phenomena prevail at 

 Sutton. The Carboniferous Limestone below the Sutton Stone has 

 been washed by the Liassic seas ; and corals and shells, some of 

 them identical with those of Brocastle, are attached to the surface 

 of the limestone, and have also passed down into its fissures, and 

 are with difficulty removed from its more ancient matrix. At the 

 Sutton quarries the conglomerate I propose hereafter to inter- 

 calate is not seen, the Sutton Stone resting there immediately upon 

 the Carboniferous Limestone. 



a. Local Deposition of the Sutton Stone. — In the railway-section at 

 Shepton, p. 505, no Liassic beds are present which indicate a condi- 

 tion of sea-bottom like that presented by the Sutton Stone ; but 

 when the former are followed to the edge of the Carboniferous 

 Limestone, they assume identical lithological characters. It is not 

 necessary that the beds thus changed should always be on the same 

 geological horizon ; for it has been shown that at Ewenney a Sutton- 

 stone condition is interposed between granular Liassic limestones, 

 and that probably at Laleston a Sutton Stone older than that at 

 Sutton is found. At Broadfield Down, near Bristol, the Rhaetic White 

 Lias is changed into a Sutton Stone ; and at Harptree the Lima-beds 

 are also metamorphosed, though they are more siliceous than the 

 above. I believe that an examination of the Southerndown coast-line 

 will show that there also the Sutton Stone is only an abnormal (and 

 probably a shore-) deposit, accumulated on ledges, or in bays or 

 basins of Carboniferous Limestone, and that it dies out, giving place 

 to thinner and more regularly bedded Liassic limestone. 



The coast-section from Sutton, in the direction of Dunraven, can 

 be seen only at low water ; and care must be taken in its examina- 

 tion. On descending from the Sutton quarry down the face of the 

 ragged Carboniferous Limestone to the beach, a cavern (which I 

 propose to call Ko. 1) is reached, of which the Sutton Stone forms the 

 arch, the Carboniferous Limestone occupying its sides and floor. 

 A few yards beyond, cavern No. 2 is seen, where the Sutton Stone is 

 thrown down by a fault, and is found resting upon a base of conglome- 

 rate which is not to be recognized in the quarries, and which appears 

 to have filled a basin or break in the Carboniferous Limestone. It is 

 composed of large pebbles of quartz, chert, and limestone in a dense 

 blue or grey matrix, differing from the Sutton Stone above, and, un- 

 like it, is not bedded. 



As my examination was necessarily very hurried, I am unable 

 to give distances ; but still further the Sutton Stone again forms the 

 crowns of the arches of caverns 3 and 4, and also the sides, the 

 darker conglomerate just mentioned being at its base, all above 

 belonging to the true Sutton Stone, which here becomes very much 

 thicker. It is next seen resting once more upon the Carboniferous 

 Limestone, becomes much thinner, accommodating itself to the irre- 



