DELESTE The Geologic Time Scale Activity 10
Storyboard Text
- The Age of Earth
- Geologic Time Scale
- Evolution of Major Life Forms
- The Earth is at least as old as the oldest rocks on the planet. So far, the oldest rock minerals discovered on Earth are crystals that are at least 4.404 billion years old. These minuscule crystals were discovered in Australia. Similarly, the Earth cannot be older than the solar system. The solar system's age of 4.57 billion years is the oldest possible age for Earth. As a result, the Earth's age ranges between 4.4 and 4.57 billion years.
- Evolution of Major Life Forms 1.2
- Earthquakes. Eruptions of volcanoes Significant eroding. Meteorites collide with the Earth. The very first signs of life. Extinction in large numbers.
- Evolution of Major Life Forms 1.3
- Single-celled organisms similar to bacteria were the first life forms. These early life forms were, of course, very simple, allowing for the evolution of more complex life forms. It wasn't until about 610 million years ago that the first multicellular organisms appeared. During the next ten million years, an event known as the Cambrian Explosion occurred, which resulted in the evolution of many different types of organisms. This rapid evolution could have been triggered by environmental changes that made the Earth's environment more suitable for a wider range of life forms.
- Plants and fungi did not emerge until about 500 million years ago. They were quickly followed by arthropods (insects and spiders). The amphibians arrived around 300 million years ago, followed by mammals around 200 million years ago and birds around 150 million years ago.
- Many organisms that lived a long time ago are no longer alive, according to fossils. Species extinction is common; in fact, it is estimated that 99 percent of all species that have ever lived on Earth are extinct.
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