When discussing a thread of history, it's hard to go earlier than the formation of continents on the Earth, which first happened 3.3 billion years ago. It technically isn't even history, since it is not written, and happened in prehistory, measured in geological epochs and millions of years. Geology plays a part in this thread of history, which brings the continents together into Pangea, forms the coal seams that drove the industrial revolution, and brought the Scotch-Irish from their homeland to the Americas to settle in the Appalachian mountains, which strikingly resemble the mountains of Scotland -- for good reason.

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