Earth Origins (00:47)
The origins of Earth can be found in matter, minerals, rocks, and other materials. Billions of years ago, Earth was a ball of molten rock and metal. Since cooling, the planet has been reshaping itself with geological, biological, physical, and chemical processes.
Geologic Time (04:18)
Learn the timeline of life form development from primitive to humans. Scientists use a geologic time scale to examine Earth's lifespan;mass extinctions are the elimination of several species at once. Compare sudden vs. gradual events.
Matter, Minerals, and Rocks (10:27)
Everything on Earth is made of matter. Earth materials can be divided into solids, liquids, and gases. Learn the most common elements in the Earth's crust, how rocks form, and the three main types of rock.
Clues to Earth's Past (01:18)
Scientists have evidence suggesting the Earth is approximately 4.54 billion-years-old and that life began 3.8 billion years ago. Evidence includes: radioactive dating, geologic layers, and fossils.
Radioactive Dating (03:32)
Radioactive dating observes the amount of radioactive decay found in a material. This method allows scientists to learn when a material was created or died.
Fossils and the Law of Superposition (06:35)
The law of superposition states rocks at the bottom of stacks are older than those at the top. Fossils provide clues about organism lifespans and what Earth was like during a particular era.
Distribution of Organisms (01:28)
Distribution helps scientists learn about past land configurations. Tectonic plates cause land masses to move. Learn the principle of uniformitarianism.
Credits: Investigating Earth's Past (00:34)
Credits: Investigating Earth's Past
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