Geophysics S-waves in the outer core. This indicates that the outer core is liquid, because liquids cannot support shear. The outer core is liquid, and the motion of this highly conductive fluid generates the Earth's field. The inner core, however, is solid because of the enormous pressure. Reconstruction of seismic reflections in the deep interior indicate some major discontinuities in seismic velocities that demarcate the major zones of the Earth: inner core, outer core, mantle, lithosphere and crust. The mantle itself is divided into the upper mantle, transition zone, lower mantle and "D′′" layer. Between the crust and the mantle is
International Association for Engineering Geology and the Environment of and the development of measures for prevention or remediation of geologic hazards. Engineering geology embraces: the definition of geomorphology, structure, stratigraphy, lithology and groundwater conditions of geological formations; the characterization of the mineralogical, physico-geomechanical, chemical and hydraulic properties of all earth materials involved in construction, resource recovery and environmental change; the assessment of the mechanical and hydrologic behaviour of soil and rock masses; the prediction of changes to the above properties with time; the determination of the parameters to be considered in the stability analysis of engineering works and of earth masses; and the improvement and maintenance of the