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4
|
occurs when plant roots grow in cracks in rocks
|
5
|
the breaking down of rock
|
6
|
occurs when water freezes in cracks in rocks
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7
|
the carrying away of broken down rock
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8
|
an extinct ocean species
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|
|
|
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1
|
remains of plants and animals that lived a long time ago
|
2
|
where the oldest layer is found in a canyon
|
3
|
largest canyon in North America
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|
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