It means that in the Cretaceous period plankton lived along the shoreline and, when they died, they created large deposits of chalk on the seabed. When the seas receded they drained through the chalk and created soil which, millennia later, turned out to be great for growing cotton. So the ancient Cretaceous shoreline became land where lots of slaves lived. Now those areas have large African American populations, who tend to vote Democrat.
Now that is inter-connectedness I didn’t even realise was possible.
