A geological survey is one that records geologically significant features in a specific area. They can also refer to a government institution that holds geological information for using in geoscience research to benefit the wealth and health of that particular nation. Examples include: Geoscience Australia, United States Geological Survey and Geological Survey of Canada.
There are a huge number of methods used to conduct surveys, and the methods used will depend on a variety of factors, including the size of area to be covered; the depth of the land that the survey needs to record; the types of features to be recorded and more.
Survey methods can be divided into two broad categories: extrusive surveys and intrusive surveys. Extrusive geological surveys look at geological features on the surface of the Earth – i.e. features that are visible if you were to walk across the land. Intrusive surveys are much more complex, and look at features below the surface.
Methods for extrusive surveys are much simpler than intrusive and in many cases simply involve a walk-over survey where the geological surveyor will observe rock formations such as outcrops, crevasses, sink holes and more.
Intrusive methods can be very expensive and used very advanced apparatus to complete. In many cases the survey needs to cover areas that are several miles below the surface of the Earth. Intrusive methods can include machine-driven boreholes, remote sensing, satellite imagery and aerial photography.
What are they used for?
There are many purposes to surveys; in fact they’re some of the most important types of surveys that we use.
Mining companies make great use of geological and land surveys, and they rely on them to choose where to dig out their next mine site. Mining companies will usually hire a geologist and geological surveyor to create a geological survey or an area of land that they suspect could be an ideal site for a mine. The geological survey will tell them whether or not there are the raw materials they are after below the Earth.
These surveys are also used to assess if there are any geologic hazards that people should be aware of. They can help assist in mitigating damage due to natural disasters.
Intrusive surveys tell us what types of rocks are below the surface, which can be beneficial for a range of purposes. For example, certain minerals and rock formations can indicate that there are water deposits underground – which can be very important in areas with water shortages.
United States Geological Survey
The USGS is an agency of the U.S. government. Almost all countries in the world have their own survey that contains a huge amount of information and data on the landscape of the country, including where it’s natural resources are and what natural hazards threaten the land.
The surveying department is huge and is divided into four different categories: geology, geography, hydrology and biology – each with smaller subdivisions within them.
An example of one of the sectors where the Geological Survey becomes incredibly important to Americans is the Earthquake Hazards Program. The Earthquake Hazards Program uses data from the Geological Survey to monitor earthquake activity around the world.
The USGS also has a department that creates geological surveys in space – Astrogeology Research Program. They are currently working on a National Volcano Early Warning System to improve early detection of the 169 active volcanoes across the USA.