The Rev. W. Buckland on the Plastic Clay Formation. 279 



11. Dark red clay partially mottled and mixed with grey clay 4 



12. Soft loam, composed in its upper region of fine yellow 



micaceous sand, mixed with flakes of a delicate ash 

 coloured clay, which become more abundant in the 

 deeper portions of the stratum, and having its lower 

 regions much iron-shot, and occasionally charged with 

 ochreous concretions, and decomposing nodules of 

 iron pyrites. It is used to make soft bricks for arches 11 



Total 57 



13. Alluvium composed of clay, sand, and gravel, the gravel 



chiefly consisting of chalk flints, both rolled and angu- 

 lar, with a few pebbles of quartz, and of brown com- 

 pact sandstone. This alluvium is covered by vegetable 

 mould ------------»- — 



The oysters of No. 2 are remarkably perfect when first laid open, 

 and seem to have undergone no process of mineralization ; they 

 soon fall to pieces by exposure to air and moisture. The chalk 

 flints contained in it are many of them in the state of small rounded 

 pebbles ; in others the angles are unbroken. Both varieties are 

 covered with a crust of greenish earth of the same nature with the 

 green particles in the sand. The angular flints appear to have been 

 derived from the partial destruction of the bed of chalk immediately 

 subjacent, of which the upper surface in contact with the sand is 

 considerably decomposed to the depth of about a foot, and its 

 fissures and numerous small tubular cavities (the latter derived ap- 

 parently from the decay of organic substances,) are filled with gra- 

 nular particles of the green earth and siliceous sand of the incumbent 

 stratum. 



2 n 2 



