70 



Now these three sections show that the sands of Dorset are, 

 considered the equivalents of the Inferior Oolite of the Cotteswolds 

 on the one hand, and of Ham Hill, Somerset, on the other. 



Ham Hill has always been a puzzle to the geologist ; but if we 

 place it on the same horizon as the so-called " Lias Sands " at Brad- 

 ford, the difficulty is at once cleared up. 



Mr. Moore, in his paper " On the Middle and Upper Lias of the 

 South-west of England," speaking of II am Hill, says : 



The workable freestone at this spot is 58 feet thick, and almost 

 entirely composed of comminuted shells, united by an irony cement, 

 and is a remarkable deposit ; for, although attaining so considerable 

 a thickness, it does not appear to be represented in any other 

 locality. It has been largely worked for centuries, and yields a 

 very excellent stone, of a light-brown colour, due to the presence of 

 carbonate of iron, an analysis of the deposit proving it to contain 14 

 per cent, of metallic iron."* 



The best Gloucestershire equivalent of this bed is to be seen in 

 the straight wall of rock at Crickley Hill, near Cheltenham, which 

 latter section we consider the equivalent of the freestone-beds at 

 Ham Hill, and the sands with shelly oolite interpolated in slabs at 

 Bradford Abbas, Babylon Hill, and the adjacent district. 



The following list of fossils from the freestone at Ham Hill and 

 the shelly oolites of Dorset can nearly all be matched in the lower 

 beds of the Inferior Oolite of Gloucestershire : 

 Belemnites compressus, Blainv. Pecten lens, Sow. 



tricanaliculatus, Ziet. annulatus, Sow. 



subtenuis, Simp. discites, Goldf. 



abbreviatus, Mill. , other species. 



Nautilus latidorsatus, D'Orb. Gervillia Hartmanni, Goldf. 



inornatus, D' Orb. Pinna Hartmanni, Ziet. 



Ammonites jurensis, Ziet. Avicula complicata, BucJcm. 



Moorei, Lycett. Astarte elegans, Sow. 



opalinus, Rein. pullus, Rom. 



Edouardianus, D'Orb. obliqua, Desk. 



Murchisonse, Sow. , other species. 



, other species. Trigonia, costated species. 



Ostrea bullata (?) clavellated species. 



Buckmanni, Lye. (?) (Grypheea). Lucina bellona, If Orb. 



* Proceedings of the Somersetshire Archaeological and Natural History Society, 

 vol. xiii. 1865-Gb 1 . 



