JR. H. Tiddeman — Age of Gower Raised Beaches. 441 



2. Tt was solidified before the intrusion of the granophyre, as the 

 latter contains a great number of xenoliths of it, which have under- 

 gone great alterations through the action of the acid magma. 



3. The granophyre has absorbed a considerable quantity of the 

 basic material, thereby altering its own composition and giving rise 

 to the crystallization of hornblende and mica, two constituents which 

 we have to consider as not belonging to the original granophyre 

 magma. 



4. In the solidification of the granophyre two stages can be 

 distinguished, the first giving rise to the formation of the rectangular 

 orthoclase crystals, which crystallized in parallel intergrowth with 

 the plagioclase xenocrysts, the second forming a kind of groundmass 

 in which fresh quartz crystallized, while the orthoclase filled up the 

 remaining spaces. 



III. — On the Age of the Eaised Beach of Southern Britain 



AS seen in Gower.^ 



By E. H. TiDDBMAN, M.A., F.G.S., of H.M. Geological Survey. 



(Communicated by permission of the Director -General of the Geological Survey.) 



GOWER has a reputation for its caves with their bone-beds, and 

 for its raised beaches, but to the matter of its Glacial Drifts 

 "very little attention has been paid. 



Some of the caves were known to and noted by Dean Buckland.* 

 The caves were long and diligently explored by Colonel Wood of 

 Stout Hall, and the results carefully collated by Dr. Falconer. A 

 great number of the bones are exhibited in the Swansea Museum. 

 Mr. Starling Benson, who lived at Swansea, has left an account of 

 Bacon Hole, and Dr. Falconer has incidentally alluded to other caves 

 in describing the animal remains. 



These three observers noted the fact that the cave fauna, which 

 included Hycena, Elephas antiquus, and Bhinoceros hemitoechus, was 

 found in bone-beds in the shore caverns and rested on or above a 

 cemented shelly conglomerate, which was evidently a raised beach, 

 for it formed a floor across the cave at from 10 to 30 feet above the 

 level of the present beach. This conglomerate was found to contain 

 shells which could not be distinguished from those of the littoral 

 zone on the present beach. 



It was recognized that the beach must have been made when the 

 sea was at that higher level, and that the bones could not have been 

 accumulated until the coast had been raised above the old beach- 

 level. But the further reasoning, which was chiefly concerned with 

 the age of the bones, was that, the beach being evidently rather 

 recent, the bones must be more recent. Falconer did not appear 

 quite content with this, and called in Prestwich to assist in finding 

 out what relation, if any, the bone-deposits and raised beach bore to 

 the Glacial deposits. 



Prestwich appears to have worked from the west along the coast 

 to Bacon Hole, but not to the east. He reported : " With respect to 



^ Read before the British Association, Section C (Geology), Bradford, Sept., 1900. 

 ^ " Eeliquite Diluvianee." 



