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Depends on how long ago it was. Two billion years ago? We wouldn't find traces of their industrial activity in rocks - almost all the rocks are gone. We woul
by AnimalMuppet 3y ago
Depends on how long ago it was.
Two billion years ago? We wouldn't find traces of their industrial activity in rocks - almost all the rocks are gone. We wouldn't notice evidence of mining activity - those mines have been buried by sedimentation, subduction, or vulcanism. We wouldn't find it in atmospheric gas isotopes - those isotopes have long since decayed.
Now if it were 10 million years ago, it is much more likely that we would know.
- pfdietz 3y agoMuch of the iron being mined today was deposited about 2.4 billion years ago, when ferrous iron in the oceans was oxidized and precipitated out as insoluble oxides in Banded Iron Formations. There are even petroleum deposits whose source rocks go back a billion years. And most coal was deposited in the Carboniferous (thus the name).