A borehole is a general term for any narrow shaft drilled in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including: * extraction of water or fluid (e.g., oil) or gases (e.g., natural gas or methane) * for a geotechnical investigation * for an environmental site assessment * for mineral exploration * as a pilot hole for installing piers or underground utilities This data contains a continuous log of strata for each borehole as well as for geocolumns. A geocolumn is a collection of information from an examination of exposed substrate, such as in a quarry wall or along a roadway passage.