Geology

The USGS Core Research Center (CRC) is one of the largest public core repositories in the country. It is home to 9,800 rock cores (full-diameter cores and slabbed cores), 53,000 well cuttings, over 25,000 thin sections taken from cataloged cores and cuttings, and provides a text-based and map-based well catalog search to find data and information on wells. Since 1974 the center has supplied...

The USGS Earth Mapping Resource Initiative (Earth MRI) is a partnership of the USGS, the Association of American State Geologists and other governmental, Tribal and private sector entities to update the nation’s surface and subsurface mapping, to improve our knowledge of the geologic framework in the United States and to identify areas that may have the potential to contain undiscovered critical...

Earth’s tectonic plates rest upon the asthenosphere, the upper layer of Earth’s mantle. Over short timescales, the mantle behaves like a solid. If you could reach down and grab a handful of mantle rock it would be just that; solid rock. However, over long geologic timescales the mantle can behave like a thick liquid that slowly flows at about the same rate that fingernails grow. Magma does exist...

A good approximation used by geologists is that the plates move roughly the same speed as your nails grow. However, tectonic plates move at different speeds and in different directions. We can measure crustal motion using Global Positioning Systems (GPS) that measure within a fraction of a millimeter per year. We can also estimate velocities over the span of geologic time using rocks in ocean...

Meteorites are fragments of rock or metal that fall to Earth from space. They are very rare, but many people find unusual rocks or pieces of metal and wonder if they might have found a meteorite. The USGS doesn't verify meteorites, but they have several properties that help distinguish them from other rocks: Density : Meteorites are usually quite heavy for their size, since they contain metallic...

While the USGS studies the types of rocks that can potentially form sinkholes, we don’t investigate individual sinkholes on private property. First, rule out human causes for your feature. Some sinkholes are caused by leaky underground pipes (talk to your utility company) and some are old construction pits or other buried materials that have settled. If you’re confident of a natural cause for your...

Rocks and minerals must be examined in person from all perspectives for accurate identification; they are extremely difficult to identify through photographs. You will get the best results by taking your rock or mineral to a local source where it can be handled and examined closely. Possibilities include: Your state geological survey A natural science museum A college or university with a geology...

The National Geologic Map Database (NGMDB) is an archive of geoscience maps (including geology maps), reports, and stratigraphic information for the United States. The NGMDB contains information on more than 90,000 maps and related geoscience reports published from the early 1800s to the present day, by more than 630 agencies, universities, associations, and private companies. Much of the content...

The USGS Field Records Collection is an archive of unpublished field notes, maps, correspondence, manuscripts, analysis reports, and other data created or collected by USGS Geology Discipline scientists during field studies and other project work. The collection is located in the USGS Library in Denver, Colorado, and is available for on-premises examination during normal library hours. See the...

A soil survey is the systematic description, classification, and mapping of soils in an area. They are published by the USDA Natural Resources Conservation Service (NRCS) , formerly known as the Soil Conservation Service. NRCS soil surveys are available from several sources: Some are on the NRCS website . Published soil surveys can be found at some libraries or borrowed through interlibrary loan...

At the head of the valley in Yosemite National Park - as if on a pedestal - stands Half Dome. It is smoothly rounded on three sides and a sheer vertical face on the fourth. Half Dome, which stands nearly 8,800 feet (2,682 meters) above sea level, is composed of granodiorite, and is the remains of a magma chamber that cooled slowly and crystallized thousands of feet beneath the Earth's surface. The...

A sinkhole is a closed natural depression in the ground surface caused by removal of material below the ground and either collapse or gradual subsidence of the surface into the resulting void. A pothole is usually a fairly small feature caused by failure of paving materials, usually associated with roads, parking lots, and airports. In the colder parts of the country, potholes become more abundant...