The term geological survey can be used to describe both the conduct of a survey for geological purposes and an institution holding geological information.
A geological survey is the systematic investigation of the subsurface of a given piece of ground for the purpose of creating a geological map or model. A geological survey employs techniques from the traditional walk-over survey, studying outcrops and landforms, to intrusive methods, such as hand augering and machine driven boreholes, to the use of geophysical techniques and remote sensing methods, such as aerial photography and satellite imagery.
A Geological Survey can also be a national or federal institution employed to maintain the geological inventory and advance the knowledge of geosciences for the benefit of the wealth and health of the nation.
In the United States, the 50 state surveys are coordinated by the Association of American State Geologists.
Some examples of national geological surveys are listed here:
Individual states or provinces may also have a geological survey. Examples include: