ABSTRACT
This chapter describes geological investigation methods. Similarly to geological investigations, the extent of the ground water investigation will also depend on site conditions. In most cases, it is sufficient to install piezometers to measure the position and variation in the water table so that realistic values of water pressure can be used in design. Geophysical methods are often used in the reconnaissance or preliminary stages of a site investigation program to provide specific information as the depth of weathering, the bedrock profile, contacts between rock types of significantly different density, the location of major faults, and the degree of fracturing of the rock. The study of stereographic pairs of vertical aerial photographs or oblique terrestrial photographs provides much useful information on the larger-scale geological conditions at a site. Other features that may be evident on aerial photographs are major geological structures such as faults, bedding planes and continuous joint sets.
