part 3] SUCCESSION of the ayojiian- at cliftojs". 233 



section are in the main ill-exposed or inaccessible, are well seen in 

 the riverside section. Attention may be drawn to a marked band o£ 

 pisolite, the nodules being shown by section to consist of JMitcliel- 

 deania associated with Spongiostroma. Above the pisolite is a 

 strong concretionary band, and this is followed after a break, which 

 suggests non-sequence, b}'" a band containing large masses of 

 Alveolites septosa. 



The existence of this break suggests that the boundary between 

 S^ and Dj be drawn here. All the regular iSeminula-hed rock- 

 types — concretionary and Semi nil la bands and white banded 

 china-stones — are, however, met with for a further 40 to 45 feet 

 above the Alveolites band, and then, although there is no marked 

 lithological break, the D fauna comes on in full force. 



Series on the left bank as repeated by the fault. — There 

 are no exposures on the left bank in the immediate neighbourhood 

 of the fault which passes just north of the mouth of Nightin- 

 gale A^alley. South of Nightingale Yalle}' the Seminula Oolite, 

 S.^ (h), is well exposed in the railway-cutting, by the road, and by 

 the riverside. In the railway-cuttino- the Seminula Oolite is seen 

 from the mouth of Nightingale Yallej^ as far as the southern end 

 of the cutting south of the short tunnel below the Suspension 

 Bridge. The roadside exposure is better than that in the cutting, 

 and includes, in addition to the upper part of S^ (5) [the Semimda- 

 Oolite], the main part of S., (c). The Clionetes bands of the lower 

 part of S.^ (c) crop out below the Suspension Bridge, while the 

 china-stones and pisolites forming the upper part of S.^ (c) are seen 

 in the roadside and riverside exposure, though most of the latter 

 is inaccessible. Very little is seen of the Concretionary^ Beds, 

 S2 {d')^ in the railway-cutting, and nothing by the road or 

 riverside. 



(li) The Dibunop)hy limn Beds. (Thickness^aljout 559 feet.) 



These rocks extend from the New Zigzag path to the Obser- 

 vatory-Hill fault. 



(1) T)y The Lower Dihunopliyllum Beds. (Thicknes3 = 

 about 375 feet.) — The D^ Beds are seen at the top of the slope 

 south of the Grreat Quarry and in its continuation, the woods of 

 * Fairyland ' ; also in the railway-cutting from the New Zigzag 

 path to the mouth of the tunnel behind Point Villa, in Bridge- 

 Valley Road, and in the exposures by the road and riverside as far 

 as Point Villa. D. may be taken to commence in the main section 

 at the level-crossing to the Zigzag path. The coarse red oolite, 

 which is very characteristic of the D beds, is referred to by Mr. E. 

 B. Wethered-i as 'the New Poad oolite.' He describes the large 

 oolitic grains of this horizon as consisting in many cases of tubules 

 assigned to Girvanella ducii. Only in one case (A 133), a rock 



1 Q. J. G. S. vol. xlvi (1890) p. 272. " 



