J. BTJCKMAN ON THE CEPHALOPODA-BEDS OF 



exceeds 28 or 30 feet in thickness, 

 of which from 8 to 10 feet belong 

 to the lower subdivision. The 

 upper subdivision immediately 

 underlies the Fuller's Earth ; and 

 its light colour, lithological struc- 

 ture, and general poverty in or- 

 ganic remains readily distinguish 

 it from the hard, brown, more or 

 less massive or rubbly limestone 

 beneath, which is everywhere very 

 f ossiliferous " *. 



Now we take it that, although 

 the learned Dr. Holl is right as re- 

 gards the position of the Dorset 

 Cephalopoda-bed, he is not so in 

 supposing that the lower members 

 of the Inferior Oolite all thin out 

 in Dorset — our view being that 

 quite 100 feet of the sands, with 

 its occasional bands of shelly 

 oolite, as these occur at Bradford 

 Abbas, really represent the lower 

 oolitic mass of Leckhampton and 

 Crickley, in Gloucestershire ; and, 

 in fact, our Dorset sands repre- 

 sent the lower freestones of Glou- 

 cestershire. 



The connexion between the 

 sands of one place (Babylon Hill) 

 and the building-stones on the 

 same horizon at Ham Hill is 

 shown in the accompanying sec- 

 tion (fig. 1). 



At Ham Hill the equivalent of 

 the sand-bed at Babylon Hill is a 

 reddish brown freestone, appa- 

 rently made up of comminuted 

 shells. At Babylon Hill the 

 brown sandy beds present occa- 

 sional courses of comminuted 

 shelly oolites. 



The two sections here placed in 

 juxtaposition (fig. 2) are remark- 

 able for their dissimilarity at first 

 sight ; but if the brown sands were 

 a little more indurated (and the 

 presence of a few more shells or 

 a little more lime might well 



* Quart. Journ. Gcol, Soc. vol. xix. 



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