T. RiGCx 





classifies surface geology by a consideration of the subsoil, the areas 

 A, A^ should be classed as valley gravels. 



The area B, map 2, which appears ou the geological map as boulder 

 clay, seems, from field observations, to be rather different in texture 

 from boulder clay soils. The soil is a darkish loam containing 

 numerous small flints. A deposit of valley gravel material seems to 

 have sufficiently altered the surface soil to justify its being classed 

 as belonging to the valley gravel soil formation. 



With the exception of these small areas indicated above, each soil 

 series coincides in area with a geological formation. 



The chief agencies producing different soil formations in the soil 

 series are (1) river wash causing deposition of coarser grained material 

 on the Oxford clay and boulder clay formations. 



(2) Slight changes in upper and lower beds of a geological formation : 

 e.g. in greensand the dark sands are always overlying the brown sands, 

 and redland is held by Mr TealU to be a transition bed between green- 

 sand and gault. 



1 Dr Bonney, Geology of Cambridgeshire. 



