1867.] IIARTT — ON CARBONIFEROUS LIMESTONES. 213 



clayey sandstone, etc., crop out under the drift. Some of the 

 harder beds extend from top to bottom of the cliff, but owing to 

 the softness and friable nature of the marly beds, and the way in 

 which the beds of limestone are broken up by the action of the 

 weather and hidden by drift and dehris, the section is not easy to 

 work out. Fortunately, the line of strike of the beds is such as 

 to carry them out on the sloping shore, and though they are much 

 hidden by shingle and mud deposited by the turbid Avon, we are 

 able to gather material for the piecing together of our section, 

 and occasionally to gain a clue as to the arrangement of the beds 

 which is not given on the cliff. 



Beginning at the beds of the toll-house, and going thence 

 southerly along the shore, we find the following succession of 

 beds : — 



The first rocks seen at the toll-house are beds of limestone, 

 having a strike of E. 15 ° S., and a dip of 65 ° to the north- 

 ward, and of which a thickness of about twelve feet is visible. In 

 the upper part these limestones are, in their weathered state, 

 cream coloured, earthy, soft, and highly laminated, but with some 

 compact bands. They afford fucoids of a slender, flattened 

 cylindrical kind, without carbonaceous coating, a Productus of the 

 Cora type, exactly like that so common in a reef just south of the 

 bridge ; and a Bakevellia-like shell. In the middle portion is a 

 band of soft, earthy, light lead-colored limestone, apparently full 

 of fucoids, and with a few fragments of shells. In the lower part 

 there is a not very compact, light brown, weathered limestone of 

 a beautiful oolitic structure. Then follows, in descending order, 

 a bed of very friable, fine-grained, greenish sandstone, cemented by 

 carbonate of lime, which is succeeded by a bed of the same 

 character, but of a deep red color from the presence of iron ; but 

 this has several greenish layers. This bed occupies the shore for 

 a distance of about seventy-five feet. In the lower part it is much 

 obscured by rubbish. The cliff is then occupied for a distance of 

 about thirty feet (horizontal) by a limestone of a loose texture 

 and a light blueish color mottled with white, and probably altered 

 by the action of the weather. The bed is much fractured and 

 hidden by dehris. Then succeeds an irregular mass of breccia, 

 composed of angular fragments of limestone, and this rests on beds 

 of Jight lead-colored, highly laminated calcareous shales, and lime- 

 stone bands: thickness, six feet; strike, E. 15° S. ; dip, 25° 

 northward; fucoids. Underlying this is a highly vesicular limestone, 



