Summary The present investigations have shown that the till at Hurlford, Ayrshire, is fissured and that a very definite fissure pattern exists. The nature of the fissures and influence of weathering, overburden pressures and stress release have been established and new scalar property classification especially designed for tills have been successfully employed. A close relationship between fissure fabric, slope stability and directional shear strength characteristics has been found and the mechanism of slope failure at Hurlford has been identified to be the opening and softening of fissures in the till. The three-dimensional shear strength anisotropy of the Hurlford soil has been shown to be outside of the bounds of applicability of conventional sample size—shear strength relationships which assume random fissure patterns in clays.