The Gatun structure is a possible eroded impact crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

. It is named after the nearby Gatun Lake

Gatun Lake

Gatun Lake is a large artificial lake situated in the Republic of Panama; it forms a major part of the Panama Canal, carrying ships for of their transit across the Isthmus of Panama....

 in Panama

Panama

Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

. It was first discovered in 1972 by geologist

Geologist

A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...

 Bob Stewart and later studied by Livio L. Tornabene from the University of South Florida

University of South Florida

The University of South Florida, also known as USF, is a member institution of the State University System of Florida, one of the state's three flagship universities for public research, and is located in Tampa, Florida, USA...

 Department

Academic department

An academic department is a division of a university or school faculty devoted to a particular academic discipline. This article covers United States usage at the university level....

 of Geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

.

The structure is estimated to have formed about 20 million years ago. This would place the event in the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 epoch. Despite the considerable erosion

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

, it was possible to estimate the original diameter

Diameter

In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...

 to have been 2.7 to 3 km, assuming the impact hypothesis is correct.

Although diagnostic evidence of impact has not been reported, evidence favoring an impact origin include the recovery of possible impact glass

Impactite

Impactite is an informal term describing a rock created or modified by the impact of a meteorite. The term encompasses shock-metamorphosed target rocks, melts and mixtures of the two, as well as sedimentary rocks with significant impact-derived components .-Some localities:*Nördlinger Ries...

at the site. Alternatively, the site may be of volcanic origin.

External links

• Planetary society article

.