Sedimentary rock indicates the current or past existence of ___.

water

lava

plants and animals

carbon dioxide

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Choose ALL the answers that apply.


The crust is:

the thinnest layer

made of large pieces called plates

mostly made of silicon dioxide

the outermost layer of the earth

also called the hydrosphere

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The ozone layer _____.

is part of the troposphere

is used to send radio signals

protects the earth from UV radiation

is made of charged ions and free electrons

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