part 8] sucoEssiois" or the ayoin'ian at cliftois^. 223 



On the left bank it is well seen in Quarry 2, in the neighbouring 

 riverside exposure where the band of patchy dolomitization near 

 the top may be noted, and by the road. The upper part is poorly 

 exposed in the railway-cutting south of Quarry 2. 



((J) The SijriiKjotlii/ris Beds. (Tliickiiess = about 418 feet.) 



(1) C^. The Lower Syringotliyris Beds. (Thickness 



=about 183 feet.) 



C, («). The laminosd dolomite. (Thickness = about 

 98 feet.) — The lower portion of the laminosa dolomite forms the 

 highest beds in Black Kock Quarry, and is seen also in the river- 

 side exposure. The upper beds are well seen in the Grull}'' Quarr}^ 

 and in the riverside section, while small exposures occur on the 

 wooded dip- slope between the Black Rock and Grully Quarries. 



The lower surface of the laminosa dolomite shows suture-jointing 

 with the top of y, and calcite-patches similar to those of Z are 

 frequent in the lower beds. As in the Grower area, the majority of 

 the rocks were originally crinoidal limestones (A 56), but are nearly 

 always strongly dolomitized. Most bands are converted into 

 uniform dolomite, often enclosing crinoidal ossicles. Occasionall}'', 

 however, a band occurs in which, though some dolomitization has 

 taken place, the original character of the rock is not obliterated. 

 Certain bands from the lower part of the laminosa dolomite show 

 brecciation, the pieces reaching a length of 1^ inches. The pale 

 colour of the laminosa dolomite contrasts strongly with the dark 

 colour of the dolomites in Z., and y. 



Although, as at Grower, there is no marked break between the 

 Caninia Oolite and the laminosa dolomite, the line of division may 

 (as in the Avon paper) be taken at the top of the ' Suboolite-Bed ' 

 (A59«),a dolomitized limestone containing abundant Glionetes 

 and Ortliotetes. This bed may be seen both in the quarry and in 

 the riverside exposure, but is best shown in a mass of rock at the 

 top of the bank between the road and the railway. 



On the left bank of the Avon the laminosa dolomite forms the 

 highest beds of Quarry 2, and is well exposed in the railway-cutting 

 between Quarries 2 & 3. The lower part is also seen b}^ the road 

 and by the riverside. The Suboolite-Bed, not very well seen in 

 the railway-cutting, is well exposed at numerous points in the 

 irregular dip-slope which bounds Quarry 3 on the north, the 

 bedding-planes being often covered with Clionetes and Ortliotetes. 



C^ (Z>). The Caninia or Grully Oolite. (Thickness =:about 

 90 feet.) — Exposed in the Gully Quarry, at the northern end of 

 the cutting south of the quarry, by the road, and in the riverside 

 exposure. This band is very uniform in character throughout. 

 The oolite-grains, which are embedded in a matrix of crystalline 

 calcite, are small as compared with those in the D beds. A large 

 proportion of them are formed round foraminifera, others round 



Q. J. G. S. No. 307. s 



