real clue for correlation on palaeontological grounds — affinity only, through, a few species in that richly peopled sea, being shown by our succeeding Rhaetic beds.
It is not, however, without interest that we should reexamine the Sutton, Portcaul, Bendrick, and Barry beds, on the coast of Glamorganshire, where St.-Cassian and Muschelkalk types occur in a white calcareous breccia or conglomerate resting immediately upon the Carboniferous limestone and below the zones of Ammonites angulatus and A. planorbis.
The Madreporaria are truly significant, and of high Mesozoic antiquity, even admitting the great vertical range or persistency of many St.-Cassian corals in time and their diffusion in space.
Chronologically, however, we have much to learn relative to the true succession and correlation of the Triassic and Rhaetic series of this country with reference to that of Western and Central Europe.
On purely physical grounds we have also much to do ere we can attempt to parallel the Muschelkalk (Calcaire Coquillien) with beds in the western or midland counties of England, although we may attempt it, and look for its equivalent in the calcareous breccia or conglomerate at the top of the Banter, and base of the Keuper series in the centre of England — the position in time held by the dolomitic or reptilian conglomerate of the Bristol area.
That the calcareous breccia above mentioned should be classed with the Keuper rather than the Bunter is, I think, clearly established.
The chief explanation, however, of the probable reason of the absence of the Muschelkalk in Britain would appear to be the received fact that the " close of the Bunter-Sandstone period in England was accompanied by a general elevation into dry land of the whole of the Triassic area, in which condition it remained throughout the period of the Muschelkalk"*, — this gap, unconformity, or break in the British series of the Trias, being represented on the Continent by the highly fossiliferous " calcaire coquillien," or Muschelkalk.
Mr. Hull throws out the suggestion† that the St.-Cassian beds, which contain so large an assemblage of organic remains, both of Palaeozoic, Mesozoic, and peculiar forms, in somewhat abnormal positions, because there is still some uncertainty regarding their affinities to the British series, may not improbably, in different portions, " represent a continuous series of calcareous deposits, representing both the Permian, Triassic, and Rhaetic beds of England."
The absence, however, in the dolomitic conglomerate of the Bristol area, of all organic remains except the two genera of Dinosauria, and those at present confined to it, forbids all attempts at correlation based upon palaeontological research.
- Hull, Mem. Geol. Surv. England and Wales, " Trias, and Perm. Rocks of
the Midland Counties," 1869, p. 106.
† Ib. p. 9.
