The recording of geophysical and geologic data recovered from a borehole. Geophysical borehole logs can be used in conjunction with drill cuttings, sidewall samples, and cores to establish the geologic succession in the well. This information can then be interpreted geologically. The logs can be used to estimate formation porosity, jointing, fluid properties, hydrocarbon saturation, and formation pressures. Water wells are often logged by devices to detect water flows, levels of inflow, and such water properties as temperature and electrical conductivity.