Earth has been bombarded by asteroids and comets throughout its 4.5 billion year history. While the vast majority burn up in the atmosphere, some of the larger ones have impacted the surface, leaving behind massive craters. Today, around 190 impact craters have been identified on Earth. Here is a detailed look at the 10 largest confirmed impact structures our planet has to offer.

1. Vredefort Crater

The granddaddy of them all, South Africa’s Vredefort crater is the largest and one of the oldest impact structures known. The original crater is estimated to have been 250-300 km (155-186 mi) in diameter, though erosion has worn away all but the central uplift. This remaining dome is about 90 km (56 mi) across.

The Vredefort impact occurred approximately 2.02 billion years ago when an asteroid 10-15 km wide slammed into what is now the Free State province. The collision would have vaporized a huge volume of rock in a cataclysmic explosion. Shatter cones and shocked quartz found at the site provide clear evidence of an extraterrestrial origin.

Today, the Vredefort Dome is a UNESCO World Heritage Site recognized for its geologic significance. The impact exposed ancient Archean rocks over 3 billion years old that were originally buried 10-25 km underground. Studying these unique formations has provided insights into early Earth processes.

The dome is home to four towns – Parys, Vredefort, Koppies and Venterskroon. Parys is the largest and serves as a tourist hub, while Vredefort and Koppies depend mainly on agriculture. The dome has been subject to property development in recent years, leading to concerns about environmental impacts. However, it remains an important site for impact crater research.

2. Chicxulub Crater

The Chicxulub crater on Mexico’s Yucatan Peninsula is famed as the impact that wiped out the dinosaurs 66 million years ago. With an estimated diameter of 180 km (112 mi), it is the second largest crater on Earth, though its structure is not exposed at the surface.

The impactor is thought to have been an asteroid 10-15 km in size. Its collision would have triggered global devastation – launching debris into the atmosphere, igniting fires, and sending tsunamis crashing into coastlines. A layer of iridium-rich clay found worldwide provides a telltale signature of the event.

In the decades since the crater’s discovery, drilling has revealed a peak ring of uplifted rock at the center. Peak rings are a characteristic of the largest impact basins in the solar system. Chicxulub’s is the only known example on Earth, with the rest buried under sediments or eroded away.

The impact vaporized huge volumes of sulfur-bearing rock, releasing as much as 325 gigatons of sulfur into the atmosphere. This may have caused years of global cooling and acidified the oceans. Geologic evidence also suggests the impact ignited fires across the globe and triggered massive tsunamis in the Gulf of Mexico.

3. Sudbury Basin

Ontario, Canada is home to the 130 km (81 mi) wide Sudbury Basin, the third largest impact structure on Earth. The crater formed 1.85 billion years ago after the impact of a 10-15 km wide asteroid. Subsequent erosion and deformation has obscured much of the original crater shape.

The Sudbury Basin is one of the richest mineral deposits on the planet, producing nickel, copper, platinum, palladium, gold, and other metals. These ores formed when the impact fractured the crust, allowing magma to well up from below. As the melt slowly cooled, valuable metals accumulated in the magma chamber.

The basin is an important economic resource for Canada. Over $1 trillion worth of metals have been mined from the site since the late 1800s. The region is dotted with mines, smelters, and refineries to process the ores. Mining will likely continue for decades to come as new deposits are discovered.

Sudbury is also a prime location for impact crater research. The high level of erosion has exposed rocks from deep within the crater, allowing scientists to study impact-related deformation. Drilling projects have sampled impact melt rocks and breccias to better understand crater formation processes.

4. Popigai Crater

The remote Popigai crater lies in northern Siberia, Russia. An asteroid roughly 5-8 km wide excavated the 100 km (62 mi) diameter basin 35 million years ago. Because of its far north location and relatively young age, Popigai is one of the best preserved large craters on Earth.

When the impactor struck, the area was rich in graphite deposits. The immense pressures and temperatures of the impact transformed the carbon into diamonds. Popigai’s diamonds are not gem-quality, but could have industrial uses. The Russian government has estimated the crater may hold trillions of carats worth of diamonds.

The crater is a challenge to study due to its isolated location. It lies north of the Arctic Circle in a wilderness of tundra and taiga forest. The nearest city is over 400 km away. Despite the difficult access, several Russian scientific expeditions have explored the site.

Popigai has a well-defined rim and central uplift. Impact melt rocks and breccias are abundant, as are shatter cones and shocked quartz. The crater has not been deformed by later geologic processes, providing an excellent snapshot of a fresh impact structure.

5. Manicouagan Crater

Known as the “Eye of Quebec”, Manicouagan is a 100 km (62 mi) wide annular lake in Quebec, Canada. The crater has been heavily eroded, but a 70 km (43 mi) diameter inner ring is still visible from space. The structure is approximately 215 million years old.

The impactor is estimated to have been 5 km wide. The lake that fills the inner ring is an important reservoir, and the central peak is thickly forested. Because of its visibility and accessibility, Manicouagan has been extensively studied by impact crater scientists.

Manicouagan formed in a region underlain by ancient metamorphic and igneous rocks of the Canadian Shield. These rocks were shattered and uplifted by the impact, then eroded to form the ring-shaped depression. Impact melt rocks and breccias are found throughout the structure.

The lake is used for hydroelectric power generation and is a popular destination for fishing and boating. The central peak hosts a unique high-altitude ecosystem that has been protected as an ecological reserve. Ongoing research at Manicouagan is focused on understanding impact crater formation and evolution.

6. Acraman Crater

South Australia’s Acraman crater is 90 km (56 mi) in diameter and 580 million years old. The structure is so heavily eroded that little of the original crater morphology remains. Lake Acraman fills a 20 km wide depression at the center.

Evidence for the Acraman impact comes from the presence of shatter cones and impact melt rocks. Ejecta from the crater has been found over 300 km away in the Flinders Ranges, where it is associated with some of the earliest known animal fossils.

The impactor was likely 4-5 km in size. It struck an area of folded sedimentary rocks, vaporizing a huge volume of material. The crater then collapsed and eroded over hundreds of millions of years, leaving only a subtle topographic signature.

Acraman has been a focus of research into the environmental effects of large impacts. The crater formed at a time when Earth’s atmosphere contained little oxygen. The impact may have vaporized water, releasing oxygen and hydrogen. It’s hypothesized this could have caused a spike in atmospheric oxygen, paving the way for the evolution of complex life.

7. Chesapeake Bay Crater

Buried under hundreds of meters of sediment, the Chesapeake Bay crater lies hidden under the waters of Virginia and Maryland. The 85 km (53 mi) wide structure formed around 35 million years ago when a 3 km asteroid or comet struck the shallow ocean that covered the area at the time.

The western part of the crater is actually exposed on land, forming a unique geology. Most of the crater lies under the bay, however, where it has been imaged by seismic surveys. Drilling has brought up shocked minerals and breccias that confirm an impact origin.

The Chesapeake impact would have vaporized huge volumes of ocean water, likely causing a short-term increase in atmospheric humidity. Tsunamis from the impact scoured the seafloor and washed over nearby land areas. Thick deposits of impact debris have been found in Virginia and North Carolina.

Today, the buried crater influences the region’s hydrology. The fractured rocks provide pathways for groundwater movement, affecting the distribution of fresh and saline aquifers. The crater is also thought to be the source of the North American tektite strewn field – a widespread deposit of glassy debris ejected from the impact.

8. Morokweng Crater

Morokweng is a deeply eroded impact structure in South Africa’s Kalahari Desert. The visible crater has a diameter of 70 km (43 mi), but it may have originally been over 340 km (210 mi) wide. The age is estimated at 145 million years old.

In the 1990s, a scientific drilling project into the crater’s central uplift brought up a surprising find – fragments of the actual meteorite. Analysis showed it was an ordinary chondrite, the most common class of stony meteorite. It is very rare for pieces of the impactor to be preserved in large craters.

The Morokweng impactor would have been 5-10 km in size. It struck an area of ancient continental crust, vaporizing large volumes of rock. The crater then experienced a complex history of collapse, erosion, and sedimentary infill.

Morokweng is a difficult site to study because of its remote desert location and deep erosion. Geophysical surveys have provided clues to the crater’s original size and structure. Drilling has sampled impact melt rocks and breccias, as well as the surprising meteorite fragments.

9. Kara Crater

The Kara crater is located on the coast of the Yugorsky Peninsula in northern Russia. It is 65 km (40 mi) wide and approximately 70 million years old. The original rim has been completely eroded away, leaving just the central uplift exposed.

The crater is actually one of a pair. The nearby Ust-Kara crater is 25 km (16 mi) wide and the same age, suggesting they formed from a binary asteroid impact. The two craters are sometimes considered a single impact structure.

The Kara region was covered by a shallow sea at the time of the impact. The craters were soon buried by marine sediments, which protected them from erosion. Subsequent uplift and erosion has re-exposed the structures.

The Kara craters have been a target for oil and gas exploration. The fractured rocks provide potential reservoirs for hydrocarbons. Drilling has also yielded important scientific data on the subsurface structure of the craters.

10. Beaverhead Crater

Rounding out the top 10 is the Beaverhead crater, which straddles the border of Montana and Idaho in the United States. The structure is highly eroded, but is estimated to be 60 km (37 mi) in diameter and around 600 million years old.

Shatter cones were first discovered at Beaverhead in the 1990s, providing convincing evidence of an impact origin for the unusual geology of the area. Ongoing erosion in the crater has exposed some of the oldest rocks in North America, dating back 2.7 billion years.

The Beaverhead impact occurred in an area of ancient sedimentary and volcanic rocks. The impactor was likely 4-5 km wide, large enough to melt and vaporize a huge volume of target rock. The crater then experienced a long and complex history of erosion and deformation.

Today, the Beaverhead structure is a rugged wilderness of mountains and valleys. The area is popular for hiking, camping, and fishing. Geologists continue to study the exposed rocks, searching for clues to the crater’s violent past.

Summary

Earth’s impact craters are more than just geological oddities – they are windows into the ancient past. Each one tells a story of a catastrophic collision that shaped the course of our planet’s history. As more craters are discovered, we gain a clearer picture of the violent forces that have molded Earth’s landscape over billions of years.