Answer:
4 billion years
Explanation:
Scientists have found the oldest known rocks on Earth. They are 4.28 billion years old, making them 250 million years more ancient than any previously discovered rocks. Earth formed about 4.6 billion years ago from a disk of gas and dust circling the sun.
The variable you would need to keep track of is hight
A ruler-like symbol used to measure distance on a map is a scale. It shows the ratio of the distance on the map to the actual distance.
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Increasing "Pressure or Temperature" is used to identify the layers of the atmosphere
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