An Analysis of the Areal Distribution of Soil Size Facies on the Lower Greensand Rocks of East-Central England by the Use of Trend Surface Analysis

Abstract

AbstractProgressive fitting of linear, quadratic and cubic partial trend best-fit surfaces to median grain size (X1, in mm.) and percentage of silt and clay sizes (X3) of soil samples taken from fifty locations on the Lower Greensand outcrop between Ely and Leighton Buzzard in east-central England permit up to about 40 per cent of the total sums of squares to be “explained”. The successively higher levels of mathematical generalization of regional soil size distribution indicate a decrease in soil grain size towards the south-east, a disparity between the alignment of the soil facies and the strike of the present outcrop, and the existence of zone of abnormally coarse soil facies just to the west of the line of the rivel Ivel. These three features of the regional distribution of soil sizes are interesting in that they correlate with observations which have been made on the regional distribution of bedrock size facies. Finally, a suggested correlation is made between the local zones of small median grain size and abnormally high proportions of silt andclay soil sizes—isolated as “deviations or residuals” from the fitted regional surfaces—and localities where small admixtures of glacial drift (evidenced by the presence of flints) have been observed.