416 STRATIGRAPHICAL GEOLOGY 



The stratigraphical variations of this series will be best explained 

 by taking first the Bajocian and following it across England from 

 south to north, and then doing the same for the Bathonian. A 

 tabular correlation will be found on p. 427. 



Inferior Oolite or Bajocian 



Southern Counties. In Dorset the limestones of this stage 

 are thin, and the lowest zone, that of Lioceras opalinum, is repre- 

 sented partly by sand and sandstone, the beds being about 1 1 feet 

 thick at Chideock, near Bridport, and 5 feet at Burton Bradstock 

 (see Fig. 130). The overlying zones are brown, ironshot limestones, 

 which at Chideock are about 8 feet thick, but at Burton they are 

 barely 3 feet. 12 Farther north, however, near Beaminster, the 

 opalinum zone is about 16 feet and the limestones above about 5 

 feet, making a total of 2 1 feet ; but the uppermost zonal horizon 

 is not everywhere the same, and the surface of the uppermost bed, 

 whatever it may be, is always eroded, either planed off and 

 coated with oysters or worn into irregular hollows. 



Between Yeovil and Sherborne the limestones properly 

 belonging to the Inferior Oolite are again very thin, though well 

 exposed in numerous quarries, and the succession given by 

 Mr. Buckman is : 



Feet. 



Limestone with Stepheoceras Humphriesianum . . . 1 to 5 



,, Lioceras concawim 3 to 4 



,, Ludwigia Murchisonce . . . . 1 to 5 



Sandy stone with Lioceras opalinum 1 to 2 



About 10 



In the Mendip district by Bruton, Doulting, and Frome the 

 Inferior Oolite is entirely absent, having apparently been raised 

 into a broad, low anticline, the upper part of which was eroded 

 and destroyed in the interval between the Bajocian and Bathonian 

 epochs, so that the beds of the latter rest directly and unconform- 

 ably on those of the Upper Lias or Toarcian. 



North of the Mendip ridge the lower beds of the Inferior 

 Oolite come in again with a pisolitic limestone at the base, succeeded 

 by oolitic freestones and ragstones of much greater thickness than 

 in Dorset or Somerset. The following is a generalised table of the 

 succession found in the Bath and Cotteswold areas : 13 



