DEPOSITS IN" THE BRISTOL DISTRICT. 



69 



within the veins shows, hy its frequently being in very thin laminae, 

 that it has been deposited slowly. It is desirable to bear in mind, 

 whilst comparing the same facts in the Bristol district, that in the 

 quarries above noticed the limestone of these Secondary mailings is 

 often left standing out as butresses by the workmen, whilst they 

 work back between them for the purer Carboniferous beds. 



Postpliocene, Liassic, and Bhcetic Deposits. The Microlestes- 

 Quarry. — On the Shepton road, immediately west of the hamlet, 

 there is a large quarry on each side facing the road. The first, 

 on the south, is the Micro Testes- quarry ; in the other, inclined 

 Carboniferous Limestone has been worked between thick veins of 

 Middle Lias, the matrix of which occasionally showed carbonate of 

 lead and barytes. The rubbish-tippings from the limekiln have 

 since obliterated these points ; but I have preserved them in pho- 

 tographs. It is probable that all the veins on this side of the 

 hamlet differ from and are to the south of those in the large 

 section east of the river. 



In my former examinations of the M icrolestes- quarry I was told 

 by the workmen that they had occasionally crossed a fissure down 

 which, by the aid of a rope, a man might descend ; but, as it was 

 becoming dangerous, it was filled up. Prom this I have suspected 

 the presence of a Postpliocene cavern at the spot; but although it 

 has not been found, they have worked back upon a vein filled with 

 bones, which I have little doubt may be connected with one. It is 

 about a foot in thickness, and, like all the other fissures and their 

 infillings, appears to have its own special individuality. Like an 

 ordinary mineral vein, the walls have vertical mineralized layers, the 

 innermost being large crystals of dog's-tooth spar. Towards the top 

 there are angular pieces of Carboniferous Limestone, which below 

 give place to material composed of about one third of brown marl, 

 crystals of carbonate of lime, and dismembered jaws and bones of 

 Arvicola and frogs, with, rarely, small vertebras of birds and fish. 

 The jaws of Arvicola are very numerous, whilst their vertebras and 

 other bones are scarce. They appear to belong to A. arvalis or A. 

 saxatilis. Bones of the larger mammalia, though few, including ox 

 and deer, were found. Amongst them was found a tooth not to be 

 distinguished by itself from a human incisor ; but the subsequent 

 discovery of the remains of wolf leads to the inference that it may 

 belong to that animal, the difference in the incisors being with diffi- 

 culty distinguished. Several Rhaetic teeth, showing from their worn 

 condition that they are derived, and a few Carboniferous-Limestone 

 corals and shells are mixed with the above, as well as pebbles of 

 haematite and bog-iron ore. 



The deposit, with its Rhaetic remains, was in a north-and-south 

 fissure a little west of the above ; but it is now all but exhausted. 

 Without reference to other mineralized veins in which no organisms 

 have been found, it will be seen that at Hoi well alone, and in the 

 line of a single quarry of but a few hundred feet length, Post- 

 pliocene, Liassic, Rhaetic, and Carboniferous-Limestone formations are 

 represented. These later deposits are the rule, not only where they 



