500 ME. E. E. L. DIXON AND DE. A. VATJOHAN ON [Nov. 1 9 1 1, 



As in the case of North-Western Gower, attention will be paid 

 chiefly to the differences between this district and those previously 

 described. 



Cleistopora Zone, K. — Probably equivalent to the Lower 

 Limestone Shales. All the groups seen in North-Western Gower 

 appear to be present, and in the following account are referred to 

 under the same numbers as those on p. 496. 



1. Modiola phase, Km. This group includes a 5-foot band of 

 conglomerate (exposed north-west of Rhossili rocket-house) of red- 

 brown quartz-pebbles, measuring up to half an inch in diameter^ 

 with larger pebbles of fossiliferous mudstone or shale, the whole 

 in a matrix of calcareous sandstone which encloses, also, reddened 

 and rounded crinoid-ossicles like those in limestones of a-type. The 

 conglomerate is both overlain and underlain by ostracod-shales with 

 limestones and sandstones, but probably lies near their base ; 

 the junction of those below with the underlying Upper Old Red 

 Sandstone is not exposed. The thin limestones interbedded with 

 the shales are chiefly of a type usual at this horizon, that is, most 

 of them contain a mixed fauna of crinoids, brachiopods, ostracods, 

 lamellibranchs, small Bellerojrfion-like gasteropods and Orthoceras, 

 besides fragments of contemporaneous sediments, including phos- 

 phates. 



2. As in Pembrokeshire, the standard part of K l commences 

 with a group of quartzitic sandstones (Rhossili), and the parallelism 

 is maintained in the shales immediately below Group 3, which, as 

 exposed at the north-west foot of Hardings Down, are distinguished 

 by the markedly nodular character of their interbedded limestones. 



3. As in North-Western Gower (and Pembrokeshire); exposed 

 at Hardings Down. 



4. Not seen. 



Zaphrentis Zone, 1 Z. — In South- Western Gower, Z consists 

 largely of limestones, dolomites, though frequent, being subordinate. 

 Shaly bands are found, but at considerable intervals, through much 

 of the lower part of the zone : and cherts, with beekitized fossils, 

 have a considerable upward range (beekite being abundant in the 

 lowest beds — some part of Z y — exposed in the anticline at Worms 

 Head, 2 and cherts, with beekite, occurring for several hundred feet 

 above). 



As usual in this zone, the limestones are largely crinoidal and 

 rather thinly-bedded, and the dolomites dark grey and finely crys- 

 talline. The fauna is tabulated on pp. 544-45. 



1 First recognized in this district by Dr. Gubbin & Dr. Vaughan, Proc. 

 Bristol Nat. Soc. ser. 4, vol. i (1905) pp. 50-52, 54. 



2 The lowest beds in this anticline have been referred by Dr. Gubbin & Dr. 

 Vaughan (op. cit. pp. 50 & 54) to Z 2 on insufficient evidence. Their horizon 

 is probably lower than that of the lowest beds at Rhossili, rather than above 

 as stated by those authors, and it is agreed that the Rhossili beds (op. cit. 

 pp. 51 & 54) belong to Zi. The beds at both places were once considered by 

 myself to lie at the base of the zone (West Gower Memoir, p. 15), but a 

 re-examination of the district, though leaving the age as Z t unquestioned, has 

 thrown doubt on their basal position, especially as regards the beds at Rhossili. 



