146 THE BATH OOLITE PERIOD. CHAP. 



(Interval, probably blue clay.) 



Yellow and white sand and sandstone, plants 15 feet 



Brown ferruginous sandstone 15 >> 



Ironstone of good quality 1 2 



Below is Upper lias clay. 



The interval, above mentioned, is occasioned by a fault which has 

 traversed all these strata. Very few fossils occur in the sands or 

 in the ironstone at this place. 



FULLER'S-EARTH ZONE. (Smith.) 



In the country round Bath the two principal masses of oolitic 

 rock are separated by a considerable body of calcareo-argillaceous 

 marls and clays with imbedded strata of stone, often soft, less 

 frequently compact and solid, rarely oolitic. The thickness of these 

 beds near Bath is found to be as much as 150 feet; but as we 

 proceed northward, the fuller's-earth series grows thinner con- 

 tinually, and finally dies out in the valley of the Windrush, about 

 Barrington ; so that in the country round Burford, the two oolites 

 referred to are no longer separated by this argillaceous band, but 

 are brought into contact k . 



In other places, as at Stonesfield, blue clay of small thickness 

 is seen, and may be regarded as a feeble equivalent of the fuller's- 

 earth group. Through a great proportion of its range the fuller's- 

 earth zone yields fossils much allied on the whole to those of the 

 Inferior oolite below, and in a less degree to those of the Great 

 oolite above. They are not distinctive, unless the remarkable 

 prevalence of Ostrea acuminata in their bands can be so regarded. 

 Belemnites and ammonites are rarely seen in it; yet one canali- 

 culated species is recorded near Bath by Smith in his ' Stratigraphical 

 System,' and again in Dorsetshire by Mr. Buckman, Rhynchonella 

 media of Sowerby (R. varians, Dav.) is prevalent near Bath, but 

 not in Gloucestershire. 



GREAT OOLITE GROUP. 



Three portions may be distinguished in the Great oolite of 

 Gloucestershire and Oxfordshire, viz. : 



k Lonsdale Geol. Soc. Proc., i. 414. Hull, in Memoirs of Geol. Survey, Sheet 44. 

 1857. 



