This specialty volume contains 34 papers pertaining to the natural behaviour of diverse geomaterials found in different parts of the world. Each paper is organized along the outline: location and distribution, engineering geology, composition, state and index properties, structure, engineering properties, quality / reliability of data with reference to methods of sampling and testing, and relation to engineering problems. This extensive body of collated knowledge is integrated by three overview papers covering engineering geology, mechanical behaviour and engineering implications. Topics: overview papers; marine clays; estuarine clays; lacustrine clays; stiff clays; sands and other cohesionless soils; residual and other tropical soils; weak rock.