The United States Geological Survey, also called USGS, is one of the many departments in the U.S. government.

USGS scientists study the entire landscape of the country. They study natural resources, including some of the country's most beautiful plains, valleys, mountains, and bodies of water. USGS scientists also study anything, natural or artificial, that can harm these natural resources.

The USGS also studies things like air quality and water quality. Measuring pollutants in the air and water in different areas of the country tells scientists where pollution is heavy. Pollutants in the water of a specific region may indicate that the region’s aquifer is contaminated. The USGS can investigate and study the problem further.

The USGS was created in 1879. Congress created the new department to study and keep track of all the public lands, minerals, and resources in the country. After the 1803 Louisiana Purchase, the need to study western lands increased tremendously. The Louisiana Purchase was more than 2.1 million square kilometers (829,000 square miles) of land, which more than doubled the size of the United States. There was simply much more land to keep track of, and the USGS was created to keep track of it.

Today, there are roughly 10,000 scientists, technicians, and other staff that work for the department. Some of the branches of science represented by the USGS include cartography, or mapmaking; seismology, or the study of earthquakes; volcanology, or the study of volcanoes; and climatology, the study of patterns in Earth’s atmosphere.

Major Sciences
Even though USGS studies everything from the atmosphere to plant life to rock formations, the department focuses on four major sciences: biology, geography, geology, and hydrology.

Biology is the study of living things. A biologist working for the USGS may study invasive species, for instance. An invasive species is an organism that is not native to an area and is threatening the health and population of the native species in the area. For example, USGS keeps track of zebra mussels (Dreissena polymorpha), which are crowding out native species and causing problems with shipping in the Great Lakes.

A USGS biologist may also focus on human health. The biologist may track the spread of West Nile virus, or keep a list of harmful pollutants in air, dust, soil, and water.

The USGS maintains data on "animals as sentinels of human health." This information recognizes that the health of animals can often be an early warning system to threats to human health. Animals interact more directly with the environment than people do, so they respond more quickly to environmental changes. Symptoms and changes in the behavior of animals, from bats to worms, are monitored by USGS biologists.

Geography is the study of Earth and its land. The surface of the land is constantly changing. Some causes of change are natural, such as wildfires, earthquakes, and volcanoes. Some changes are artificial, including agricultural and industrial development.

The geographers of the USGS study geospatial patterns, or significant features of the landscape. One of the primary programs of the USGS is the Geographic Analysis and Monitoring Program (GAM). The goal of GAM is to monitor the changes occurring on the surface of Earth and analyze the consequences of these changes. GAM assesses Earth's land cover—the material on a specific portion of Earth’s surface. The GAM Program established an erosion monitoring station on the coast of the Beaufort Sea in Alaska, for instance. This station used a camera and measuring instruments to document coastal erosion in the area.

Geology is the study of how Earth changes over time. The layers under the surface of the planet are a record of how Earth has changed. The chemical composition and location of rocks and minerals tell geologists how landmasses have shifted or changed over time. Often, there is material in the rocks and mineral layers, such as fossils and fossil fuels.

USGS geologists study mineral resources of the United States. This includes minerals such as gold, as well as coral found in the coastal waters of Florida. Geologists consider the human needs for such minerals, as well as the impact mining would have on the environment.

Hydrology is the study of water and how it moves, changes, and shifts all around the planet. Water is probably the most important natural resource the USGS studies. Americans use about about 1.5 trillion liters (408 billion gallons) of water every day, according to the USGS.

Hydrologists study the quantity, quality, and availability of water. Hydrologists locate aquifers and measure how much water they now hold or have held in the past. They measure how quickly water supplies are drained by homes and businesses. They sample water from different areas to see what chemicals are present, and how safe the water is to drink, cook with, or use for bathing. Finally, hydrologists use technology to determine how much water is available to what areas. Some areas, like the Sierra Nevada mountains of Northern California, have healthy water resources. Other areas, like the desert of Southern California, have fewer water resources.

Location, Location, Location
One big task of the USGS is mapping just about everything in the United States. The USGS is the primary resource for research on where something is, what's around it, and what the topography of the area is.

This information can be used for all kinds of tasks, like helping ambulance drivers and firefighters find the best route to their destination, letting engineers know where to build stable buildings and bridges, and keeping people informed of local hazards like floods.

Some areas of the country, like San Francisco, California, have earthquakes. Earthquakes happen when two tectonic plates under the Earth shift, causing everything on the surface to jiggle around. When everything on the surface jiggles around, it can sometimes cause a lot of problems: buildings fall, streets get torn apart, and people get hurt. The USGS monitors these active tectonic plates. Scientists try to predict, as best they can, when an earthquake or some kind of shift will happen underneath the surface. The idea is to give people notice before a big earthquake happens, so they have time to clear out to a safe place.

USGS scientists monitor volcanoes, too, so they know roughly when one might erupt. There are many volcanoes in the state of Hawaii and Alaska, for instance. Kilauea is one of the most active volcanoes on Hawai'i. The USGS keeps a “Kilauea: Latest Update” report online.

The USGS studies more than just the surface of Earth. The USGS studies the interior of Earth and even the solar system using a technique called remote sensing. Remote sensing detects and monitors radiation (heat and light) from a specific area.

Radiation is affected by the amount of water, chemicals, and other substances in an area. Measuring radiation can tell scientists what chemicals are present in the area without actually drilling or visiting the area. Remote sensing is conducted through instruments on airplanes or satellites orbiting Earth. One of the most exciting remote imaging finds is that our moon, which looks pretty dry, can hold large amounts of water beneath its surface.

Remote sensing techniques can also be used to study the movement and behavior of wild animals, such as migration patterns. USGS remote sensing technology also helped scientists discover that chloride, a natural chemical, can harm fish and other aquatic animals. Remote sensing is able to identify rivers and streams that have large amounts of chloride, and the information can help local communities take action to protect their water and wildlife.

The USGS motto is "Science for a changing world." The world changes a little bit every day; research from the USGS helps us all deal with those changes.