This list includes potential but unconfirmed structures that are not listed on the

Earth Impact Database The Earth Impact Database is a database of confirmed impact structures or impact crater, craters on Earth. It was initiated in 1955 by the Dominion Observatory, Ottawa, under the direction of Carlyle Smith Beals, Carlyle S. Beals. Since 2001, it h ...

list of confirmed impact structures. For confirmed impact structures, see

List of impact structures on Earth This list of impact structures (including impact craters) on Earth contains the majority of the 194+ confirmed impact structures given in the Earth Impact Database as of 2024. Alphabetical lists for different continents can be found under #Imp ...

List of confirmed and possible impact structures

The following tables list geological features on Earth that are possible impact events, but for which there is currently no confirming scientific evidence in the peer-reviewed literature. In order for a structure to be confirmed as an impact crater, it must meet a stringent set of well-established criteria. Some proposed impact structures are likely to eventually be confirmed, whereas others are likely to be shown to have been misidentified (see below). Recent extensive surveys have been done for Australian (2005), African (2014), and South American (2015) craters, as well as those in the Arab world (2016). A book review by A. Crósta and U. Reimold disputes some of the evidence presented for several of the South American structures.

Overview

Russia's

Lake Cheko Lake Cheko () is a small Fresh water, freshwater lake in Siberia, near the Podkamennaya Tunguska River, in what is now the Evenkiysky District of the Krasnoyarsk Krai. It is primarily known for its proposed relationship with the Tunguska event, 1 ...

is thought by one research group to be the result of the famous

Tunguska event The Tunguska event was a large explosion of between 3 and 50 TNT equivalent, megatons that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of 30 June 1908. The explosion over ...

, although sediments in the lake have been dated back more than 5,000 years. There is highly speculative conjecture about the supposed Sirente impact (c. 320 ± 90 AD) having caused the Roman emperor Constantine's vision at Milvian Bridge. The Burckle crater and Umm al Binni structure are proposed to be behind the floods that affected

Sumer Sumer () is the earliest known civilization, located in the historical region of southern Mesopotamia (now south-central Iraq), emerging during the Chalcolithic and Early Bronze Age, early Bronze Ages between the sixth and fifth millennium BC. ...

ian civilization.Master, S. (2002) Umm al Binni lake, a possible Holocene impact structure in the marshes of southern Iraq. In: Leroy, S. and Stewart, I.S. (Eds.), Environmental Catastrophes and Recovery in the Holocene, Abstracts Volume, Brunel University, UK, 29 August – 2 September 2002, pp. 56–57 The Kachchh impact may have been witnessed by the Harappan civilization and mentioned as a fireball in

Sanskrit Sanskrit (; stem form ; nominal singular , ,) is a classical language belonging to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in northwest South Asia after its predecessor languages had Trans-cultural ...

texts.R. V. Karanth, P. Thakker, and M. Gadhavi 2006
A preliminary report on the possible impact crater of Kachchh
, Current Science, vol. 91, no. 7, October 2006 Shortly after the Hiawatha Crater was discovered, researchers suggested that the impact could have occurred as late as ~12,800 years ago, leading some to associate it with the controversial

Younger Dryas impact hypothesis The Younger Dryas impact hypothesis (YDIH) proposes that the onset of the Younger Dryas (YD) cool period (stadial) at the end of the Last Glacial Period, around 12,900 years ago was the result of some kind of cosmic event with specific details var ...

(YDIH). James Kennett, a leading advocate of the YDIH said, "I'd unequivocally predict that this crater is the same age as the Younger Dryas." These claims were criticised by other scholars. According to impact physicist

Mark Boslough Mark Boslough is an American physicist at Los Alamos National Laboratory, research professor at University of New Mexico, fellow of the Committee for Skeptical Inquiry, and chair of the Asteroid Day Expert Panel. He is an expert in the study of ...

writing for ''

Skeptical Inquirer ''Skeptical Inquirer'' (S.I.) is a bimonthly American general-audience magazine published by the Committee for Skeptical Inquiry (CSI) with the subtitle "The Magazine for Science and Reason". The magazine initially focused on investigating clai ...

'' the first reports of the impact released by science journalist Paul Voosen focused on this being a young crater which according to Boslough "set the tone for virtually all the media reporting to follow". Boslough argued, based on evidence and statistical probability, that once the crater has been drilled and researched "it will turn out to be much older." He complained that this important discovery "was tainted by connections to a widely discredited hypothesis and speculations that did not make it through peer review". The YDIH has since been refuted comprehensively by a team of earth scientists and impact experts. A 2022 study using

Argon–Argon dating Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede Potassium-argon dating, potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measur ...

of shocked zircon crystals in impact melt rocks found outwash less than 10 km downstream of the glacier pushed the estimate back to around 57.99 ± 0.54 million years ago, during the late

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

. Confirmation would require drilling almost through the ice sheet above the crater to obtain a sample of dateable, solidified impact melt from the crater. The age of the Bloody Creek crater is uncertain. As the trend in the Earth Impact Database for about 26 confirmed craters younger than a million years old shows that almost all are less than in diameter (except the Agoudal and Rio Cuarto), the suggestion that two large craters,

Mahuika Mahuika is a Māori fire deity and consort of the god Auahitūroa. Myths In some versions, she is the younger sister of Hine-nui-te-pō, goddess of death. It was from her that Māui (in some versions he is her grandson) obtained the secre ...

() and Burckle (), formed only within the last few millennia has been met with skepticism. However, the source of the young (less than a million years old) and enormous Australasian strewnfield (c. 790 ka) is suggested to be a crater about across somewhere in Indochina,Povenmire H., Liu W. and Xianlin I. (1999
"Australasian tektites found in Guangxi Province, China"
30th Annual Lunar and Planetary Science Conference, Houston, March 1999. with Hartung and Koeberl (1994) proposing the elongated Tonlé Sap lake in

Cambodia Cambodia, officially the Kingdom of Cambodia, is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline ...

(visible in the map at the side) as a suspect structure. The Decorah crater has been conjectured as being part of the Ordovician meteor event. Several twin impacts have been proposed, such as the Rubielos de la Cérida and Azuara (30–40 Ma), Cerro Jarau and Piratininga (c. 117 Ma), and Warburton East and West (300–360 Ma).World's largest asteroid impact zone found in Australia
Meteorite broke in two, leaving two craters each 200 km across. Mar 24, 2015 However, adjacent craters may not necessarily have formed at the same time, as demonstrated by the case of the confirmed Clearwater East and West lakes. Some confirmed impacts like Sudbury or

Chicxulub The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore, but the crater is named after the onshore community of Chicxulub Pueblo (not the larger coastal town of Chicxulub Puerto). I ...

are also sources of magnetic anomalies and/or gravity anomalies. The magnetic anomalies

Bangui Bangui (; or Bangî in Sango language, Sango, formerly written Bangi in English) is the Capital (political), capital and List of cities in the Central African Republic, largest city of the Central African Republic. It was established as a Fren ...

and Jackpine Creek, the gravity anomalies Wilkes Land crater and Falkland Islands, and others have been considered as being of impact origin. Bangui apparently has been discredited, but appears again in a 2014 table of unconfirmed structures in Africa by Reimold and Koeberl. Several anomalies in

Williston Basin The Williston Basin is a large intracratonic sedimentary basin in eastern Montana, western North Dakota, South Dakota, southern Saskatchewan, and south-western Manitoba that is known for its rich deposits of petroleum and potash. The basin is a ...

were identified by Swatzky in the 1970s as

astrobleme An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface ...

s including Viewfield, Red Wing Creek, Eagle Butte, Dumas, and Hartney, of which only the last two are unconfirmed. The

Eltanin impact The Eltanin impact is thought to be an impact event, asteroid impact in the eastern part of the South Pacific Ocean that occurred around the Pliocene-Pleistocene boundary approximately 2.51 ± 0.07 million years ago. The impact occurred ...

has been confirmed (via an iridium anomaly and meteoritic material from ocean cores) but, as it fell into the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

, apparently no crater was formed. The age of Silverpit and the confirmed Boltysh crater (65.17 ± 0.64 Ma), as well as their

latitude In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...

, has led to the speculative hypothesis that there may have been several impacts during the KT boundary. Of the five

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

s in descending order by area, namely the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, Indian,

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

, and

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

, only the smallest (the Arctic) does not yet have a proposed unconfirmed impact crater. Craters larger than in the

Phanerozoic The Phanerozoic is the current and the latest of the four eon (geology), geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present. It is the eon during which abundant animal and ...

(after 541 Ma) are notable for their size as well as for the possible coeval events associated with them especially the major

extinction event An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occ ...

s. For example, the Ishim impact structure is conjectured to be bounded by the late

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

-early

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

(c. 445 ± 5 Ma), the two Warburton basins have been linked to the

Late Devonian extinction The Late Devonian mass extinction, also known as the Kellwasser event, was a mass extinction event which occurred around 372 million years ago, at the boundary between the Frasnian and Famennian ages of the Late Devonian period.Racki, 2005McGh ...

(c. 360 Ma), both Bedout and the Wilkes Land crater have been associated with the severe

Permian–Triassic extinction event The Permian–Triassic extinction event (also known as the P–T extinction event, the Late Permian extinction event, the Latest Permian extinction event, the End-Permian extinction event, and colloquially as the Great Dying,) was an extinction ...

(c. 252 Ma), Manicouagan (c. 215 Ma) was once thought to be connected to the

Triassic–Jurassic extinction event The Triassic–Jurassic (Tr-J) extinction event (TJME), often called the end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, . It represents one of five major extinction events during the Phanerozoic, profoundly ...

(c. 201 Ma) but more recent dating has made it unlikely, while the consensus is the

Chicxulub impact The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore, but the crater is named after the onshore community of Chicxulub Pueblo (not the larger coastal town of Chicxulub Puerto). I ...

caused the one for Cretaceous–Paleogene (c. 66 Ma). However, other extinction theories employ coeval periods of massive volcanism such as the

Siberian Traps The Siberian Traps () are a large region of volcanic rock, known as a large igneous province, in Siberia, Russia. The massive eruptive event that formed the trap rock, traps is one of the largest known Volcano, volcanic events in the last years ...

(Permian-Triassic) and Deccan Traps (Cretaceous-Paleogene).

Undiscovered but inferred

There is geological evidence for impact events having taken place on Earth on certain specific occasions, which should have formed craters, but for which no impact craters have been found. In some cases this is because of erosion and Earth's crust having been recycled through plate tectonics, in others likely because exploration of the Earth's surface is incomplete, or because no actual crater was formed because the impacting object exploded as a cosmic air burst. Typically the ages are already known and the diameters can be estimated.

Mistaken identity

Some geological processes can result in circular or near-circular features that may be mistaken for impact craters. Some examples are '' calderas,

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

sinkholes A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water ...

, glacial cirques, igneous intrusions,

ring dike A ring dike or ring dyke is an Intrusive rock, intrusive igneous body that is circular, oval or arcuate in plan and has steep contacts. While the widths of ring dikes differ, they can be up to several thousand meters. The most commonly accepted me ...

s, salt domes, geologic domes, ventifacts, tuff rings, forest rings'', and others. Conversely, an impact crater may originally be thought as one of these geological features, like Meteor Crater (as a

) or Upheaval Dome (as a salt dome). The presence of shock metamorphism and

shatter cones Shatter cones are rare geological features that are only known to form in the bedrock beneath meteorite impact craters or underground nuclear explosions. They are evidence that the rock has been subjected to a shock with pressures in the ran ...

are important criteria in favor of an impact interpretation, though massive landslides (such as the Köfels landslide of 7800 BC which was once thought to be impact-related) may produce shock-like fused rocks called "frictionite". File:Crater lake oregon.jpg, Crater Lake, Oregon (a ''

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

'') File:Maare.jpg, Three ''

s'' in Germany File:Great Blue Hole.jpg,

Great Blue Hole The Great Blue Hole is a large Blue hole, marine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll from the mainland and Belize City. The hole is circular in shape, across and deep. It has a surface ...

, Belize (a ''

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water ...

'') File:2013-09-09 12 34 02 View of the Verdi Lake from Verdi Peaks.jpg, Verdi Lake (a '' glacial cirque'') File:Kondyor-view.jpg, Kondyor Massif or Konder (an ''

igneous intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

'') File:Melville Island salt diapir.png, '' Salt domes'' on Melville Island File:ASTER Richat.jpg, The

Richat structure The Richat Structure, or ''Guelb er Richât'' (, ), is a prominent circular geological feature in the Adrar Plateau of the Sahara The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in ...

(a '' geologic dome)'' File:Arkenu craters.jpg, The Arkenu structures (a pair of ''

s)'' File:ISS-47 Brukkaros Mountain, Namibia.jpg, Brukkaros Mountain (a '' tuff ring)'' File:Boreal Forest Ring.jpg, A '' forest ring'' in

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

Notes and references

Notes

References

Bibliography

External links

Earth Impact Database
– List of confirmed earth impact sites at the Planetary and Space Science Centre,

University of New Brunswick The University of New Brunswick (UNB) is a public university with two primary campuses in Fredericton and Saint John, New Brunswick. It is the oldest English language, English-language university in Canada, and among the oldest public universiti ...

Impact Database
(formerly Suspected Earth Impact Sites list) maintained by David Rajmon fo

US {{DEFAULTSORT:Impact craters, possible, Earth + Lists of coordinates *