Some typical values for the properties of granular soils are given in Ranges of shear strengths for clays are given in The properties of clay soils are very dependent upon their moisture content and they can be much more complex, mineralogical, than more granular soils. Consequently the range of values of properties is much greater. There are some special ‘problem’ soils encountered in the world, which give particular engineering difficulties. In many cases the properties are due to the mode of origin and/or subsequent geological history, in which environment often plays a leading role.