171 



that measurement considerably ; while at the Hamlet of Meadgate 

 or Medycat, seven miles S.E. of Bath, it cannot be estimated at more 

 than from 40 to 70 feet, and may very possibly be less. 



The presence of the " Middle Lias," or " Lias Marlstone," is one 

 of the points most difficult of identification in the Bath district, and 

 I must acknowledge, that during the few opportunities I had of 

 studying the question, I was unable to satisfy myself of the presence 

 of that deposit by any recognisable features. I am bound, however, 

 to add that Mr. Moore has satisfied himself of its existence, though 

 in an obscure form, and under altered conditions from those in which 

 it presents itself in the Cotteswold range. At Charlcombe Hill, as 

 well as on the north-western extremity of Dundry Hill, a consider- 

 able thickness of very adhesive ferruginous clay appear to occupy 

 the position of the "Middle Lias," and may very possibly be its 

 representative ; but if so, its presence is not indicated by any fossils, 

 in so far as I was able to discover, and at Meadgate the Upper and 

 Lower Lias Marls appear to pass insensibly into one another, 

 without any distinct line of demarcation, though the presence of 

 " Spirifor rostratus " about the middle of the series would appear 

 to mark the horizon of the " Marlstone." Lonsdale, in his Memoir, 

 speaks of the " Marlstone " near Bath as containing numerous in- 

 dividuals of " a large Pecten with obtuse ribs," which might be 

 attributed to P. aquivalvis ; but, inasmuch as he appropriates the 

 term " Marlstone " to certain sandy beds, interposed between the 

 Lias and the Inferior Oolite, it is plain that he refers to the " Sands" 

 interculated between these two deposits ; in which, however, I was 

 not fortunate enough to observe the Pecten in question, nor any 

 other fossil organism whatever. These " Sands" are everywhere 

 present in situ, and exhibit a series of alternating Sands and Sand- 

 stones to a thickness of from 60 to 80 feet, to which extent they are 

 exposed at Charlcombe, the only spot at which I was able to trace 

 them throughout their entire thickness, and as this Section presents 

 some features of interest, I will proceed to review it in detail. 



SECTION AT CHAHLCOMBE. 



It will be seen by reference to the map, that the village of Charl- 

 combe lies due north of Bath, niched into the hollow of one of the 

 numerous pretty combes scooped out by the action of the retiring 

 waters, when the coast-line, of which it forms a part, was slowly 

 emerging from the waves of the ancient " tertiary" ocean. The 

 direction of the Valley itself is about N.W. and S.E., and is traversed 

 throughout the greater portion of its length by a small rivulet, which 

 takes its rise in a deep gully, not far from the Church, and it is this 

 gully which affords the Section to which I have adverted. 



After passing over the entire thickness of the Lias Clays, which 



at this point I cannot estimate at less than 600 or 700 feet, the 



gully intersects the highest beds of the "Upper Lias Shales, which are 



seen dipping downwards at a considerable angle, the result 



