Robert Krulwich:
It's an image of North America as it looked during the Cretaceous
era, 129 million to 65 million years ago. As you can see, much of the
continent was still covered by water. The Deep South had a shoreline
that curled through the Carolinas, Georgia, Alabama and Mississippi, and
there, in the shallow waters just offshore, were immense populations of
floating, single-celled creatures who drifted about, trapped sunshine,
captured carbon, then died and sank to the sea bottom. Those creatures
became long stretches of nutritious chalk. (I love chalk.)
When
sea levels dropped and North America took on its modern shape, those
ancient beaches — so alkaline, porous and rich with organic material —
became a "black belt" of rich soil, running right through the South. You
can see the Cretaceous beaches in this map, colored green. McClain got
these maps from geologist Steve Dutch's website, at the University of Wisconsin, Green Bay.
And because this stretch was so rich and fertile, when cotton farmers
moved here in the 19th century, this stretch produced the most cotton
per acre. Harvests of 4,000-plus bales were common here.
Rich soil and large cotton crops equaled slaves, and now their descendants create a Democratic archipelago in a sea of Republicans.
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