26 



rocks and consisted of representatives of the Bala Series only, 

 which he was able to compare bed for bed with those of the Shelve 

 district. 



3. The Shropshire Cambrian and Uriconian. 



Naturally the fascinating rocks of Caer Caradoc and the 

 Wrekin, and those immediately overlying them, claimed some 

 attention. Callaway had described certain Shineton Shales as of 

 Upper Cambrian age, and underlying sandstones, which he paralleled 

 with the Hollybush Sandstone of Malvern, as probably earlier 

 Upper Cambrian. Below this come quartzites which, on the balance 

 of evidence, he thought likely to be pre-Cambrian. In a limestone 

 in the Sandstone at Comley he found fossils, *" the most abundant 

 being apparently trilobitic ; but it occurs in such a fragmentary 

 condition, and is of such an unusual type, that I cannot express 

 any opinion on its generic affinities." 



To these fragmentary remains Lapworth devoted his attention. 

 By the time the International Geological Congress met in London, 

 in 1888, he had collected enough to convince him that he was in 

 possession of a species of Olenellus, and when at the same Congress 

 Walcott stated that the Americans had come into line with the 

 Swedes in the opinion that Olenellus marked a Lower Cambrian 

 horizon, Lapworth f announced his discovery, and a little later 

 figured his fragments and constructed a restoration of the trilobite, 

 which he named Olenellus (Callavia) Callavei. 



Some of the consequences of this discovery were outlined in the 

 earlier of these two papers, the leading conclusions being : (i) the 

 presence of a true Lower Cambrian fauna demonstrated for the 

 first time in Britain ; (2) the existence of a new Cambrian rock- 

 facies in England different from that of Wales ; (3) the practical 

 certainty that the Uriconian rocks of the Wrekin, etc., are pre- 

 Cambrian ; (4) the very high probability that the Longmyndian 

 rocks are also pre-Cambrian ; and, if so, (5) the extreme likelihood 

 that the Torridon Sandstone, so like the rocks of the Western 

 Longmynd, would also prove to be pre-Cambrian. 



Further discoveries followed : (i) That the Wrekin Quartzites, 

 into which the sandstone containing the Olenellus limestone grades, 

 are Lower Cambrian and not pre-Cambrian, a conclusion which 

 carried with it the probability that the Lickey and Hartshill, 

 and even the Durness, Quartzites were Cambrian too ; (2) the 

 discovery by Dr. T. T. Groom of a species of Paradoxides in beds 

 above the Olenellus Limestone proving the existence of Middle 

 Cambrian beds in Shropshire, a conclusion amply verified by the 

 subsequent discovery by Lapworth of a Paradoxides limestone 



* Quart. Journ., Geol. Soc., vol. xxxiv. (1878), p. 759. 

 t 41, 46. 



