'I UK .IfKASSIC SYSTKM 399 



lenticular mass of oolitic freestone is developed with a local thick- 

 ness of 80 feet and containing Dum. Moorei ; this is known as the 

 Ham Hill Stone. 



Northward the sands thin out entirely, so that near Bath the 

 radians zone is represented entirely by clay, but is underlain by 

 sands which Mr. Buckman assigns to a sub-zone intermediate 

 between that of Lilli and that of radians, and at its base there 

 is a condensed limestone representing lower zones. 



In Gloucestershire there is another change and a different 

 succession : (1) clays representing the falciferuin and bifrons zones ; 

 (2) the Cotteswold sands, which include the zones of Harp. Lilli 

 and H. variabilis ; and finally a Cephalopoda Bed representing all 

 the higher zones in successive layers of limestone. The clays vary 

 from 50 to 130 feet, the sands are on the average 150 feet, and the 

 limestone varies from 2 to 8 feet 



2. The Midland Counties 



Rhaetic Beds. These form a narrow but continuous band 

 between the Keuper marls and the dark shaly clays of the Lias, 

 but they are rarely exposed in Worcester. In Warwickshire there 

 are exposures of the White Lias at Knowle (near Solihull) and at 

 Harbury, Rugby, Southam, and Eatington, and a good section has 

 been described at Wigston, near Leicester, where the following 

 succession was seen : 



Feet. 



2. Blue shales with two thin beds of limestone and sandstone . 22 



1. Black shales containing Schizodus cloacinus, Protocardium rhatti- 



cum, Pteria contorta, and fish teeth . . . . . .18 



A similar succession is found in Rutland and Lincolnshire. 



The Lower Lias is seldom well exposed in Oxfordshire or 

 Warwickshire, but a boring has proved its thickness to be 450 

 feet, and fairly good sections are found near Harbury and Fenny 

 Compton, where all the zones are seen except those of oxynotum and 

 armatum. 



In the counties of Leicester, Rutland, and Lincoln the Lower 

 Lias is both more accessible and more fully developed, and the 

 following succession of beds has been described : 



/"Blue clays with septaria (^Egoceras capricomus). 

 I Blue clays with thin limestones and septaria (Rhacoctras 

 Lower Lias, I ibex and Uptonia Jamesoni). 



B I Sandy clays and sands, occasionally indurated into a stone 



(Deroceras armatum}. 

 \Blue clays with small septaria (Oxynoticeras oxynotum). 



