There is evidence to support the changes in life forms over Earth's history (additions and extinctions) are often accompanied by changes in environmental conditions on Earth. Impacts, climate changes, and volcanism can produce sudden and rapid changes to environmental conditions. Many organisms cannot adapt to these sudden and rapid changes resulting in the extinction of those species. When these events are global in nature then mass extinctions occur.
Impact Events
- Earth's atmosphere protects our planet from many of the meteors that enter it. Many of the "space rocks" that reach Earth end up burning up before they even striking the surface.
- There is evidence to support the claim that numerous impacts have occurred throughout Earth's history. These impacts have had both local and large-scale effects on the environment and biodiversity.
Shooting Stars?
- Every day, Earth is bombarded with more than 100 tons of dust and sand-sized particles!
- About once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface.
- Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area.
- Only once every few million years, an object large enough to threaten Earth's civilization comes along. Impact craters on Earth, the moon and other planetary bodies are evidence of these occurrences.
The Catastrophic End to the Dinosaurs and the Mesozoic Era
There is evidence to support that the extinction of the dinosaurs and the end of the Mesozoic Era were a result of a large asteroid or comet impact on Earth. This impact forced dust and smoke to rise into the atmosphere causing rapid climatic changes, as well as the death of many of plant life and animals that depended on those plants for food.
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Topic Tips
- There have been numerous impact events throughout Earth's history.
- An impact event is theorized to have triggered the extinction of the dinosaurs at the end of the Mesozoic Era.