Craig’s Soil Mechanics, To the civil engineer, soil is any uncemented or weakly cemented accumulation of mineral particles
formed by the weathering of rocks as part of the rock cycle (Figure 1.1), the void space between the particles containing water and/or air. Weak cementation can be due to carbonates or oxides precipitated
between the particles, or due to organic matter. Subsequent deposition and compression of soils, combined with cementation between particles, transforms soils into sedimentary rocks (a process known as
lithification). If the products of weathering remain at their original location they constitute a residual
soil. If the products are transported and deposited in a different location they constitute a transported
soil, the agents of transportation being gravity, wind, water and glaciers. During transportation, the size
and shape of particles can undergo change and the particles can be sorted into specific size ranges. Particle sizes in soils can vary from over 100mm to less than 0.001mm. In the UK, the size ranges are
described as shown in Figure 1.2. In Figure 1.2, the terms ‘clay’, ‘silt’ etc. are used to describe only the
sizes of particles between specified limits. However, the same terms are also used to describe particular
types of.., First. © 1974, 1978, 1983, 1987, 1992, 1997, © 1974, 1978, 1983, 1987, 1992, 1997, 2004 R. F. Craig
© 2012 J. A. Knappett