ABSTRACT
Geophysical methods are based on the ability to detect and measure contrasts between the characteristic properties of materials. All materials exhibit some distinguishing characteristic properties. Contrasts exist owing to differences in density, electrical (conductive) properties, magnetic susceptibilities, and chemical and mineral properties. Geophysical methods provide a means to investigate these properties actively or passively. When materials are buried in the subsurface, the characteristic properties may be masked by the properties of the encapsulating materials, thereby making any contrasts between the buried and encapsulating materials indistinguishable. If a contrast is too small to be measured or does not exist, geophysical methods are useless.
