224 PEOF. S. H. REYNOLDS O]!^ THE LITHOLOGICAL [vol. Ixxvii, 



crinoidal fragments. Perfect little doubly-terminated quartz- 

 ciystals are plentiful in the upper beds (A 63) ; sometimes the 

 oolitic grains are developed concentrically round them, but more 

 often they are embedded at any point in the grain. Mr, E. B. 

 Wethered ^ gives an anah^sis and full description of this rock. 



The line of junction between the Caninia Oolite and the Caninia 

 Dolomite is very sharply defined, and at first suggests non-sequence. 

 The somewhat hregular character of the top of the oolite is, 

 however, doubtless due to subsequent solution. Much of the upper 

 part of the oolite has a reddish tinge owing to the presence of iron- 

 oxide, and the solution of the oolite has led to the concentration of 

 the iron along the line of junction. 



It is difficult to find fossils in the oolite of the Grully Quarrj'-, 

 chiefly owing to their scarcity, but parth^ because of the weathered 

 state of the rock; bands of Orthotetes and Chonetes may, how- 

 ever, be noted in the lower part. 



The Caninia Oolite is well seen in Quarry 3 on the Leigh Woods 

 side. The lowest bed which is exposed in the cutting, in the eastern 

 wall of the quarry, and at the top of the dij)-slope bounding the 

 quarry on the north, is more fossiliferous than is usual with this 

 horizon. Orthotetes creiiistria, Chonetes painlionacea, Syringo- 

 thyris laminosa, and Michelinia grandis being readil}^ found. 



(2) C^. The Upper /S'yr^'^iyo^'/iyr/s Beds, T\\e Caninia 

 Dolomite. (Thickness = about 235 feet.) — These rocks form the 

 unquarried strata extending from the Gully Quarry to the Great 

 Quarry. They are well seen in the rail wajj"- cutting, and are also 

 visible in the riverside exposm-e. They are shallow- water deposits, 

 and differ from those of Gower in that the whole series forms part 

 of a Modiola phase (the second of those occurring in the Avon 

 Section), while in Gower the upper beds are normal fossiliferous 

 limestones. Evidence of accumulation in shallow water is afforded 

 b}^ the signs of current-bedding which may be seen on some of the 

 joint-faces, and by bands of breccia (doubtless desiccation-breccia) 

 occurring near the base. The rocks consist principally of cal- 

 careous shales or mudstcnes often with ostracods (A 64), alternating 

 with bands which (originally limestone) are now more or less 

 completely dolomitized. They are in the main fine-grained dark- 

 grey or sometimes pink rocks, most of which show no structure in 

 a hand-specimen ; but in certain of the less completely dolomitized 

 bands plates of crinoids can be seen, Crinoids, however, do not 

 appear to have been important constituents of the rocks of this 

 level, most of them having originally been calcite-mudstones.-^ 

 Some exceedingly fine-grained and structureless dolomites are 

 probably dolomite-mudstone (A 73 & 85). Some of the limestones 



^ Q, J, G, S. vol, xlvi (1890) p. 271. 



" The term calcite-muds tone is used in the sense in which it was 

 employed by E, E. L. Dixon (Q..T. G. S. vol. Ixvii, 1911, p. 516) who gives a 

 full account of china-stones and other varieties of calcite-mndstone. 



