"Ragnarok: The Age of Fire and Gravel" by Ignatius Donnelly is a book published in 1883. Donnelly proposes that a massive comet struck Earth 12,000 years ago, destroying an advanced civilization and plunging survivors into a dark age. He supports his theory with geological evidence from the Great Lakes, chemically altered rocks, and ancient myths from cultures worldwide describing cosmic catastrophe, fire, floods, and prolonged darkness. (This is an automatically generated summary.)
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