Geotechnical engineering is a sub-set of civil engineering that is focused on the behavior of earth materials. Geotechnical engineers use soil and rock mechanics to find out more information about subsurface conditions, materials, and formations. In the oil and gas industry, geotechnical engineers use their expertise to analyze and examine the earth formations during the early stages of planning for construction projects. These projects could include drilling apparatuses, structural foundations, mining operations, and offshore oil platforms. Geological and geomechanical engineers are typically classified as geotechnical engineers.