Precambrian rocks<span> are mostly covered by rock systems of more recent origin, but where visible they commonly display evidence of having been altered by intense </span>metamorphism<span>. Precambrian rocks often occur in shields, which are large areas of relatively low elevation that form parts of continental masses.</span>
* there should be water
* there should be plants(life)
* there should be atmosphere
* there should be oxygen and carbon dioxide,ect,................
Carbonate rocks, like limestone <span><span>dolomite's, and chalk on earth</span> </span>
<span>all water Rivers 2% on the earth is fresh water, the rest of the Swamps 11% earth’s water
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