Layer 3 was examined in the fiela and provisionally interpreted as a Bt horizon. A sample (locaxion shown on fig.5) was examined in thin section in order to throw further light on how the layer had formed. It can be described as follows using the method and terminology of Brewer 1964, Bullock and Murphy 1979:- Homogeneous; well developed fine and meciium subangular blocky; total macrovoids (> 20 μm) 13.1%; smoothed orthovughs and channels occur intrapedally; silt-size mineral grains dominantly quartz; includes fine gravel-size flint; coarse grains angular; small grains moderately rounded; many fine void argillans (few medium); few compound ferri-argillans; few embedded argillans; common to many fine to medium matrans and matri-argillans; common to many irregular, and linear intrapedal clay concentrations; few fine to medium distinct ferromanganiferous nodules; finely mixed organic matter and medium organic matter fragments in matrix; fine organic matter and charcoal fragments in matrans; silt layers within compound matrans ana matri-argillans; silasepic; porphyroskelic.