WATSON — THE HEMATITE DEPOSITS OF GLAMORGANSHIRE, 247 



they occupied when alive. Yet in the district I am describing, such 

 testimony can be found, and the date, geologically, of the period when 

 those elevations occuiTcd which in all probability gave airangement 

 to the present sui-face of the land, is most singularly revealed to us. 

 JSIr. David Eees, of Neath, discovered some time since some modem 

 littoral shells among the attle " from a lead-vein which traverses the 

 crop of the limestone at the Llantrissant Lead-w orks, fi'om which place 

 the shore now lies upwards of ^eighteen miles distant. The specimen, 

 which is in my possession, is figured on the adjoining page (PL IX.) 

 from a beautifully accurate drawing by Mr. S. J. Mackie, and displays 

 a limpet shell (^Patella vulgata) with two barnacles {Balanus halanoides), 

 in the position in which they adhered to the rock at the time when 

 the back of the vein was washed by the waves ; the lower part of the 

 specimen — a piece of confusedly crystallized cai'bonate of lime, in fact, 

 an ordinary veinstone — is spotted with little masses of galena, one 

 or two of the crystals of which may be seen in the cut. It would 

 be leading from the purpose of this paper to do more than remark 

 that this species of mollusck {Patella vulgata) as well as the cirri- 

 pedes (Balani), are animals inhabiting the tidal zone, and that, 

 therefore, the hmestone-ridge from which the specimen came must 

 have fringed the shore, as does the same rock now near Newton, 

 where the "backs" of lead-veins may also be seen at ebb-tide^ 

 encrusted with the same description of shells. By reference to any 

 good geological map of the district, it will be seen that the point 

 marked Llantrissant Lead-works lies apparently on the conglomerate, 

 but the veins which are close by are found really in the limestone 

 which has been exposed by the denudation of the thin cap of conglo- 

 merate. It follows from this fact, that, on the evidence of the shells, 

 the mass of land lying to the south, and occupied chiefly by lias, was 

 probably submerged until a very recent period, and that much of 

 the present disposition of the gravel-beds, as already remarked, was 

 given to them dui'ing the final elevation of the land. 



But if thus much of elevation and denudation of the land has 

 occurred, it is obvious that we must find evidence of great dislocation of 

 strata, — of beds not only bent into simple or double curves, but of 

 rents and fissures such as a succession of elevations and depressions, 

 with their concomitant disturbances, would be sure to effect. And, 



