The Largest Impact Crater On Earth Flashcards
(29 cards)
What was the size of the asteroid that killed the non-avian dinosaurs?
About 10-15 km in diameter.
Where is the crater from the dinosaur-killing asteroid located?
In the Gulf of Mexico.
What is the Vredefort impact structure?
The largest known impact crater on Earth.
How long has the Vredefort crater held the record for the world’s biggest crater?
For 2 billion years.
Where is the Vredefort crater located?
In South Africa, near Johannesburg.
How wide is the Vredefort crater estimated to be?
Around 280 km wide.
Why is it hard to measure the Vredefort crater exactly?
Because the crater has eroded over time.
How large was the asteroid that created the Vredefort crater?
About 25 km across.
How fast was the Vredefort asteroid moving?
Around 15 km per second.
What period likely had the largest impacts on Earth?
The Hadean Period, about 4 billion years ago.
How far have rocks from the Vredefort impact been found?
As far as modern-day Russia, which at the time, was closer to South Africa than today due to continental shift but was still 2000km away!
What was the supercontinent situation 2 billion years ago?
Continents were joined together in a supercontinent.
How far apart were impact-thrown rocks 2 billion years ago?
About 2,000 km.
What type of life was present during the Vredefort impact?
Cyanobacteria and other microbial life.
What did cyanobacteria begin doing around the time of the Vredefort impact?
Photosynthesizing and pumping oxygen into the atmosphere.
What caused a years-long winter after the dinosaur-killing asteroid impact?
Dust in the atmosphere blocked out the sun.
Why would a years-long winter be harmful to cyanobacteria?
Because they are photosynthetic and need sunlight to make food.
What is a shatter cone?
A cone-shaped rock with cracks pointing towards the impact site, formed by shock waves.
What do shatter cones indicate?
A dramatic impact, such as an asteroid strike or nuclear explosion.
What was previously thought to be the cause of the dome at the Vredefort site?
Volcanic activity.
What caused the dome at the Vredefort site?
Rebound from the asteroid impact.
What is a craton?
The ancient, stable core of a continent made of old continental crust.
What did the impact at Vredefort do to the craton?
Brought it closer to the surface.
Why is the exposed craton at Vredefort important?
It allows researchers to study Earth’s geology from 3 billion years ago.
