by Barry G. Clarke (Author) At some time 30% of the world's land mass was covered by glaciers leaving substantial deposits of glacial soils under major conurbations in Europe, North and South America, New Zealand, Europe and Russia. For instance, 60% of the UK has been affected, leaving significant glacial deposits under major conurbations where two thirds of the population live. Glacial soils are composite soils with significant variations in composition and properties and are recognised as challenging soils to deal with. Understanding the environment in which they were formed and how this affects their behaviour are critical because they do not always conform to classic theories of soil mechanics.