THE OOLITE FORMATION. 



203 



and other rough work, and provincially known by the name 

 of pea-grit. 



2. The next in order is the oohte, or roestone, about fifty 

 feet in thickness, and rests immediately upon the pisoUte, 

 without any intermediate layer of clay, though it is some- 

 what coarser towards the bottom of the bed; this bed 

 contains many small shells, but none very remarkable ; the 

 following is a rough list of those which I have found at 

 Leckhampton Hill. 



Univalves. Patella rugosa.* 



Turitella 1. 



Cerithium 1. 



Trochus 1. 

 Bivalves. Pecten 2. 



Gerveljia 1. 



Ostrea plicatula. 



And on the Cirencester road, 



Pyrina myteloides. 



3. Freestone. This bed occurs in immense blocks, is of a 

 light colour and very fine grain, is soft when first taken out 

 of the quarry, but hardens on exposure ; the bed is from 

 forty to fifty feet in thickness, and is well exposed in the 

 numerous quarries of this neighbourhood, whence it is 

 obtained for building purposes, some of our best edifices 

 being built of it ; but it is apt to shell off with hard frosts. 



The lithological character of this stone is similar to the 

 building stone of Bath ; but it must be remembered that 

 the Bath stone is a member of the great oolite formation, 



* The Patella rugosa runs all thro«gh the oolite. I believe this is the 

 first notice of its having been found inferior to the Stonesfield slate. 



