185 



out Southwards, and still higher up the bill, we enter the 

 quarry called by the workmen the " Rolling-bank." In Sheet 44 

 of the Geological Survey this escarpment is marked " tumbled 

 Oolite and undercliff," names which alike indicate the disturbed 

 condition of the beds, produced probably by a slip of the Oolitic 

 strata over the unctuous clays of the Upper Lias. 



The Lower Trigonia Grit, which is seen in situ on the plateau 

 above, has here rolled over and formed the glacis of the hill, it 

 has thereby covered the beds of the " Humpbresianus Zone" 

 which immediately underlie it. Recent workings having more 

 fully exposed these " Humphresianus" beds than formerly, I 

 have collected therefrom, a series of fossils characteristic of the 

 " Fauna " of this zone and have lately ascertained the strati- 

 graphical sequence of the beds composing this middle division of 

 the Inferior Oolite in the northern Cotteswolds. 



The " Rolling Bank Quarry " is capped by about 18 inches 

 of the "Lower Trigonia Grit," composed of loose incoherent 

 fragments of a light coloured Oolitic limestone, beneath which 

 are exposed the uppermost beds of the "^Humphresianus" zone, 

 consisting of 



No. 1. The Phillipsii-bedis a light buff coloured, compact 

 earthy limestone. Many of the blocks are composed of tbe 

 shells of Brachiopoda, of which that of Terebratula Phillipsii 

 greatly predominates. The bed measures from two to four feet 

 jn thickness, and contains, 



Lima proboscidea Sow. 



Pecten ? 



Terebratula Phillipsii. 



perovalis, 



carinata. 



Buckmanni. 



Rbynchonella spinosa. 

 tetrahedra. 



No. 2. The Roads tone-bed consists of a coarse brown fer- 

 ruginous oolitic limestone, extremely hard and crystalline, in some 

 parts traversed by sandy layers, in others, containing calcareo- 

 siliceous concretions, which have a crystalline structure and un- 

 even fracture ; it forms a durable road-material, and is raised for 

 that purpose. The bed varies from 10 to 15 feet in thickness, 

 and contains a small assemblage of Mollusca, which are nearly 

 all in a state of moulds ; a few species have their tests preserved. 

 The Trichites are very large, and sometimes well preserved in the 

 rock, but cannot be extracted entire. Pholodomya Heraultii 

 Ag., attains likewise a gigantic size. The following species occur 

 in the bed : 



Cephalopoda. 

 Ammonites d'OrbignanaViT. Brogniarti d'Orb, mm. Sow, 



