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IGNEOUS ROCKS
Lesson 1 - Page 7

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Early humans used stones in their everyday life. They did not know how they formed, but they used tools fashioned from stones. These tools were used as weapons, in agriculture, grinding food, or to build a house. Even the first wheels were made of stones.

Learning about the rock cycle is more than just identifying rocks and minerals. Rocks can hold clues of how the Earth formed and evolved through time, and it is for us to interpret ancient environments. Geology unlike other scientific fields incorporates the fourth dimension, time. As the Earth moves slowly through time, the landscape can change from cold to hot, from rainy to dry. It can melt large spans of the ocean or erode the highest mountains. As these processes of the rock cycle are at work, they are superimposed by living organisms, especially within the last billion years of time.

The interface of the Earth and life is a unique feature of the Rock Cycle. Plants require the nutrients that minerals from the rocks provide. Rocks are sometimes considered a dead science, but add water and life can come from rocks.

 
Stone weapon


Grinding stone


Tree growing from granite

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