How the Earth Was Made

There's a lot of information in How the Earth Was Made, but perhaps the most interesting relates to time. Quite often, the numbers are so staggering that scientists refer to it as "deep time," an appropriate term when one grapples with the notion that our planet is 4.5 billion years old, or that the oceans were formed by rainfall that lasted literally millions of years, or that 700 million years ago, Earth was completely covered by ice that was a mile thick, with surface temperatures reaching minus 40 degrees Fahrenheit. On the other end of the scale are numbers that seem surprisingly small: for instance, it wasn't until 220 years ago that the accepted church doctrine regarding the planet's age (no more than 6000 years, according to the Bible) was seriously challenged and that the key to its past was found in rocks, not scripture, while the discovery that dinosaurs once ruled the Earth came considerably later than that.

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