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CNN
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Scientists have long believed our planet is built upon four layers of rocks, minerals and magma deposited over millions of years of existence.
But researchers now think the world has five major layers after discovering a previously undetectable 400-mile-wide ball of iron inside Earth’s inner core. The revelation could help experts understand more about the origins of the place we call home.
And then there are the hidden layers of history beneath our feet — roads, cities and ways of life that have been covered over and forgotten with the passage of time.
As we dig down into those lost chapters, stories have a way of coming to life again.
When engineers tunneled…
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