Question

Discuss evidence of craters on Earth. you may discuss any other craters that we know of on Earth. You could also discuss the issue of craters on Earth in general.

Answer 1

Earth has about 175 known impact craters, but surely our planet has endured more bashing than that in its history.

But since two-thirds of Earth is covered by water, any asteroid impacts occurring in the oceans are difficult to find.

Most of Earth’s impact craters have been discovered since the dawn of the space age, from satellite imaging. In fact, a geologist recently discovered an impact crater using Google Earth!

Here’s Most Impressive Impact Craters, starting with #1. the largest and oldest known impact crater, Vredefort Crater, shown above, located in South Africa. It is approximately 250 kilometers in diameter and is thought to to be about two billion years old. The Vredefort Dome can be seen in this satellite image as a roughly circular pattern. What an impact that must have been!

2. Manicouagan Crater: fifth largest known impact crater. This crater is located in Quebec, Canada. It was created about 212 million years ago. Now, it is an ice-covered lake about 70 km across. This image, taken by space shuttle astronauts, shows an outer ring of rock. Close up, the rock reveals clear signs of having been melted and altered by a violent collision. The original rim of the crater, though now eroded away, is thought to have had a diameter of about 100 km.

3. Chicxulub Crater, third largest and possible dinosaur killer. The third largest impact crater lies mostly underwater and buried underneath the Yucatán Peninsula in Mexico. At 170km (105 miles) in diameter, the impact is believed to have occurred roughly 65 million years ago when a comet or asteroid the size of a small city crashed, unleashing the equivalent to 100 teratons of TNT. Likely, it caused destructive tsunamis, earthquakes and volcanic eruptions around the world, and is widely believed to have led to the extinction of dinosaurs, because the impact probably created a global firestorm and/or a widespread greenhouse effect that caused long-term environmental changes.

most astronomers believe that the Earth was once hit by a mars-sized object, an event which created the Moon. In addition to this major hit, the Earth has been struck by just as many meteorites as all the other moons and planets, and would be completely pockmarked with craters if it weren't for one thing: erosion. The Earth has several very efficient erosion mechanisms which wipe away craters and other geological formations at a very rapid rate. Wind, rain, floods, oceans, ice ages, and plate tectonics all serve to constantly recycle the surface of our planet, wiping away most of the evidence you see in abundance on other moons and planets.