How can I tell if I have found an impact crater?

There are many natural processes other than impacts that can create circular features and depressions on the surface of the Earth. Examples include glaciation, volcanism, sinkholes, atolls, salt domes, intrusions, and hydrothermal explosions (to name just a few). Prehistoric mines and quarries are also sometimes mistaken for impact craters.

Although the USGS has been involved in impact crater research, we are neither the experts nor the ultimate authority on impact craters. Canada’s University of New Brunswick Planetary and Space Science Center is the best resource for confirming a structure as an impact crater. They maintain an Earth Impact Database and provide guidelines for identification of impact craters. 

Learn more: This Dynamic Planet: World map of volcanoes, earthquakes, impact craters, and plate tectonics (2006)

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I think I found a meteorite. How can I tell for sure?

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. Meteorites have several properties that help distinguish them from other rocks: Density : Meteorites are usually quite heavy for their size, since they...

What is a sinkhole?

A sinkhole is a depression in the ground that has no natural external surface drainage. Basically, this means that when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes are most common in what geologists call, “karst terrain.” These are regions where the types of rock below the land surface...

When did dinosaurs become extinct?

Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years. If all of Earth time from the very beginning of the dinosaurs to today were compressed into 365 days (one calendar year), the dinosaurs appeared January 1 and became extinct the third week of September. (Using...

Did people and dinosaurs live at the same time?

No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs. Many scientists who study dinosaurs (vertebrate paleontologists) now think that birds are direct descendants of one line of carnivorous dinosaurs, and...

Could magnetic reversals be caused by meteorite or comet impacts?

Although extremely unlikely, it might be possible for a reversal of the Earth's magnetic field to be triggered by a meteorite or comet impact, or even for it to be caused by something more "gentle," such as the melting of the polar ice caps. Self-contained dynamic systems like Earth’s dynamo can have reversals without any outside influence...
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Date published: March 5, 2013

Iowa Meteorite Crater Confirmed

USGS Airborne Surveys Back Up Previous Decorah Research

Date published: March 15, 2001

Scientists Return to Ancient Impact Crater


March will mark the beginning of a new field season for scientists from the U.S. Geological Survey (USGS) and its cooperators who will begin drilling a second core hole into an impact structure created 35 million years ago when an asteroid or comet slammed into the ocean near the present-day mouth of the Chesapeake Bay.

Date published: July 7, 1999

"Deep Impact" in Chesapeake Bay

No, not another meteor disaster movie, but something left a big impression in the Chesapeake Bay.

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Color Shade DEM of Meteor Crater
December 31, 2018

Color Shade DEM of Meteor Crater

Color Shade of a DEM(Digital Elevation Model) of Meteor Crater.

Chesapeake Bay Impact Crater Boundaries Map
September 26, 2016

Chesapeake Bay Impact Crater

Chesapeake Bay Impact Crater Boundaries Map

Image: Gale crater
March 14, 2016

Gale crater

Infrared mosaic image of Mars Gale crater by the Thermal Emission Imaging Spectrometer (THEMIS) of the USGS Astrogeology Science Center and Arizona State University. The Mars Science Laboratory is scheduled to land in Gale crater Aug. 5, 2012.

USGS Astrogeology team members at Meteor Crater
December 31, 2014

USGS Astrogeology team members at Meteor Crater

USGS Astrogeology team members at Meteor Crater.

February 5, 2013

Chesapeake Bay Impact Crater

February 2013 public lecture, presented by David Powars

Image: Cratered cones near Hephaestus Fossae
June 7, 2007

Cratered cones near Hephaestus Fossae

Cratered cones near Hephaestus Fossae, Mars. This might look at first glance like a cinder cone, but it is more likely an impact crater. Using the shadow, one can tell that its floor is at a lower elevation than the surrounding landscape. A cinder cone would rise above the landscape. 

Cinder cones (otherwise known as scoria cones) are the most common type of volcano

March 22, 2007

PubTalk 3/2007 — Impact!

Piecing together the story of a giant meteorite crater beneath the Atlantic coast

By David S. Powars, Geologist, and R.D. Catchings, Geophysicist

  • Buried under Chesapeake Bay is a very well preserved impact structure 56 miles across and more than 2 miles deep
  • Following clues from drill holes and seismic imagery, careful
Dome within Mount St. Helens' crater, November 2004, aerial view fr...
November 7, 2004

Dome within Mount St. Helens' crater, Nov. 2005

Dome within Mount St. Helens' crater, November 2004, aerial view from the east.

Earth As Art image Shoemaker Crater
January 1, 1999

Shoemaker Crater

Resembling splotches of yellow and green paint, salt-encrusted seasonal lakes dot the floor of Western Australia's Shoemaker impact structure. The structure was formed about 1.7 billion years ago and is currently the oldest known impact site in Australia.

  • Collection: Earth as Art 2
  • Source: Landsat 7
  • Download: 
Photo of a large, deep, circular depression in the desert with an elevated rim
December 31, 1980

Aerial view of Meteor Crater, Coconino County, Arizona

Aerial view of Arizona's Meteor Crater, a 180 meter deep, 1.2 kilometer diameter bowl-shaped impact crater in Northern Arizona. The crater formed approximately 50,000 years ago by the impact of a 100,000-ton iron-nickel meteorite that was approximately 30 meters in diameter and struck at an approximate speed of 12-20 km/sec.

Aerial photograph showing a large, deep, circular depression with an elevated rim in the barren desert
December 31, 1975

Aerial view of Meteor Crater, color, Coconino County, Arizona

Meteor Crater formed approximately 50,000 years ago by the impact of a 100,000-ton iron-nickel meteorite, ~30 m in diameter, which struck at an approximate speed of 12-20 km/sec. The Canyon Diablo meteorite, so named for the small canyon to the west of the crater, exploded with the force of over 2 million tons of TNT (or about 150 times the force of the atomic bomb