BRITISH ASSOCIATION MEETING AT CAMBRIDGE. 



421 



gical phenomena he had noticed in the Carboniferous Limestones of the 

 Mendip Hills. Through the whole of this district he observed that the 

 beds had been very much fissured, and that most of them had subsequently- 

 been filled in with deposits containing numerous organic remains of dif- 

 ferent geological ages, some of which were probably as young as the Infe- 

 rior Oolite. A small roadside section at Holwell, on the south-east of 

 the Mendip, was described, in which, at the base, Carboniferous Lime- 

 stone was present ; whilst resting unconformably upon it was a dense un- 

 stratified conglomeratic deposit, containing shells of the age of the Middle 

 Lias, and on this rested thin horizontal beds of Inferior Oohte. The out- 

 crop of a mineral vein was also present in this section. Near the above 

 was a quarry 200 feet in length, within which were thirteen vertical fis- 

 sures passing down through inclined stratified beds of Carboniferous Lime- 

 stone : one of them being fifteen feet in breadth at the base of the quarry. 

 These fissures, which occupied nearly one-third of the section, had been 

 filled in by a dense variegated limestone, containing occasionally Brachio- 

 poda, Crustacea, Belemnites, and fish and reptilian remains of secondary 



In an adjoining quarry to the above Mr. Moore found a softer infilling, 

 three cart-loads of which he removed to his residence, and found therein 

 teeth of the Microle-stes, the oldest known quadruped ; various reptilia, 

 including Placodus and Thecodontosaiiru-s ; more than 50,000 teeth of the 

 LopJiodus, together with an immense number of other organic remains, 

 from the age of the Carboniferous Limestone to that of the Inferior Oolite, 

 though they appeared chiefly to have been derived from the bone-bed of 

 Ithoetic age. 



In the upper portions of some of these fissures, galena, sulphate of 

 barytes, and iron ore were occasionally present, which showed that in. 

 these cases the minerals must necessarily be of secondary age. Desirous 

 of more fully investigating this point, the author examined the mineral 

 deposits of the Mendips, in doing which he descended the Charter House 

 Mine, and obtained very interesting results. The lead mines of this dis- 

 trict had been extensively worked in the Eoman period, the slags and 

 slimes they left being now profitably re-worked. The vein-stuff of the 

 above mine was found to be very varied in its character. At one point it 

 was almost entirely composed of disjointed encrinital stems, with a few 

 corals, all much abraded by the action of water. At a depth of 175 feet, 

 Avhere the working had ceased, there occurred a deposit of blue marl eight 

 feet in thickness, which yielded 1\ per cent, of lead ore. In this marl he 

 found organic remains in the greatest abundance, and eventually succeeded 

 in obtaining about 130 species, a few being derived from the Carboniferous 

 Limestone, though the greater number were of secondary age. They con- 

 sisted of an Ammonite, Belemnites, ten species of Bracliiopoda, including 

 Zellania — hitherto found only by the author in the Upper Lias and the 

 Inferior Oolite ; also, Tliecideum, Crania, Lingula, Hhynchonella, Spirifer, 

 etc. Of univalves, there were about thirty species ; of Foraminifera, fif- 

 teen ; fish remains were abundant, consisting of teeth, scales, and bones of 

 probably fifteen species. In this clay were also blocks of stone containing 

 shells and pieces of drift-wood, the latter having been converted into jet. 



From these fcicts it became evident that the Mendip lead-veins had been 

 within the influence of the ocean during the secondary period, aiul that 

 the minerals they contained could not be of more ancient date. 



The district around Bristol was then noticed, and it was shown that 

 precisely similar phenomena occurred there in the Carboniferous Limestone. 

 At Clifton, the Thecodontosaurus had been found; and it was urged that 



