364 ME. T. F. SIBLT OK THE CARBONIFEROUS [May I906, 



Lithe easternmost exposures, however, which lie near the margin of 

 Ebbor Wood, almost due north of the water-tank, certain beds are 

 highly fossiliferous, aud have yielded the following fossils : — Pro- 

 ductus concinnus, mut. D 2 and costa tus-like variants (very abundant), 

 Pr. JiemispJiericus, mut., Pr. <p, Pr. punctato-fimbriatus, Chonetes 

 aff. comoides, Spirifer cf. bisulcatus and Ehipidomella s'p. According 

 to the Geological Survey-memoir, 1 the beds in these last exposures 

 must immediately overlie the ' Lower Limestone Shales ' and dip 

 northward ; whereas they represent a high level in D 2 , and are, in 

 all probability, succeeded conformably by the Millstone Grit on the 

 south, although it is impossible to determine their dip with certainty. 

 Farther eastward, the limestone bordering the Millstone Grit is 

 concealed by Ebbor Wood, and the Dolomitic Conglomerate soon 

 cuts off the outcrop of the Carboniferous rocks. 



(b) The SEMiNULA-Zone* 



There is not sufficient evidence to determine accurately the 

 relation of the Seminida-beds, which are exposed in Ebbor Eocks 

 and elsewhere north of the valley, to the beds of the Upper 

 Dibunophyllum-Zone. The former rocks are considerably disturbed; 

 in all the most southerly exposures they have a northerly dip, and 

 farther north they dip southward. If the beds turn completely 

 over in a short distance, there may possibly be a sequence north of 

 the quarry ; there is not room, however, for a sequence, from the top 

 of S x to the base of the Millstone Grit (about 900 feet), between the 

 mouth of Ebbor Eocks, or the exposures on the hill north-west of 

 that point, and the edge of the Millstone-Grit outcrop. The most 

 probable explanation is a fault ; but there is not evidence enough to 

 trace the course or the limits of this fault with accuracy, and the 

 matter must, therefore, be left open. 



The exposures of the Semimda-beds are as follows : — 



In Ebbor Eocks, the upper part of S x is displayed. The faunal 

 assemblage, comprising Lithostrotion Martini (abundant), Syringo- 

 pora cf. reticulata, Productus d (abundant), Pr. aff. Cora, Pr. cf. 

 semireticulatus, mut. S x , Seminula ficoides, Athyris cf. expansa, 

 A. cf. planosulcata, and Chonetes cf. papilionacea, leaves no doubt 

 as to the horizon. In the lower part of the gorge, the prevalent 

 dip is a low easterly one ; in the upper part, separated from the 

 lower by a wooded gap, the dip is about 25 c , and varies from south 

 to south-west. Here, then, is apparently a synclinal fold of some 

 kind in the Seminula-beds. 



High up on the north-eastern side of the valley, immediately 

 north-west of the mouth of the gorge, Seminida-beds are exposed in 

 a low cliff, and at several points in the fields ; the precise horizon 

 is uncertain. Here the beds have a low northerly dip. These 

 exposures lie only about 150 yards from the nearest exposure of D 2 . 



Much farther north-westward, the exposures are scanty, but they 

 afford further evidence of disturbance. Beside the footpath, about 



1 See the illustrative section, op. cit. fig. 2, p. 19. 



