Annus Mirabilis

1811 was a "year of wonders" in the Mississippi Valley. On December 16 the New Madrid Earthquake, the largest earthquake ever recorded in American history, shook the valley and caused the mighty Mississippi river to flow backwards for a few minutes and rang church bells as far away as Boston. Here's an account from the period, note the massive squirrel migration:

Many things combined to make the year 1811 the Annus Mirabilis of the West. During the earlier months, the waters of many of the great rivers overflowed their banks to a vast extent, and the whole country was in many parts covered from bluff to bluff. Unprecedented sickness followed. A spirit of change and a restlessness seemed to pervade the very inhabitants of the forest. A countless multitude of squirrels, obeying some great and universal impulse, which none can know but the Spirit that gave them being, left their reckless and gambolling life, and their ancient places of retreat in the north, and were seen pressing forward by tens of thousands in a deep and sober phalanx to the South. No obstacles seemed to check this extraordinary and concerted movement: the word had been given them to go forth, and they obeyed it, though multitudes perished in the broad Ohio, which lay in their path. The splendid comet of that year long continued to shed its twilight over the forests, and, as the autumn drew to a close, the whole Valley of the Mississippi, from the Missouri to the Gulf, was shaken to its centre by continued earthquakes. It was at this very epoch in which so many natural phenomena were combining to spread wonder and awe, that man too, in the exercise of that power with which he Creator has endowed him, was making his first essay in that region, of an art, the natural course and further perfection of which was destined to bring about yet greater changes than those effected by the flood and earthquake: and at the very time that the latter were agitating the surface, the very first steam-boat was seen descending the great rivers, and the awe-struck Indian on the banks, beheld the Pinelore [footnote: The Chocktaw name for the steam-boat, literally 'fire-canoe.' end footnote] flying through the turbid waters.