Would this post about ancient ice ages be a good GGG ping list item?
This article has some confusing information. It says the ice age occurred at the beginning of the Ordovician Period at 450 mya, however, my books are saying the OP started 500 mya and ended around 440 mya. Also the article says the last ice age was 40 mya. In fact the last five ice ages started around 1 million years ago, with the most recent starting a little over 100,000 years ago.
There are those who wonder if the Ordovician extinction even may have been caused by an asteroid/comet/meteor strike. Are there any large craters identified from that period? Below are what two books have to say about that extinction.
"Chesapeake Invader" by Wylie Poag (book about the Chesapeake Meteor, which struck 34 mya leaving a crater 50 miles in diameter stretching north from Norfolk, VA to Exmore on the Delmarva Peninsula) - "The oldest and second-largest Big Five mass extinction took place at the end of the Ordovician Period. This event is noted for drastic reductions in the brachiopod and trilobite populations. Altogether, around 70 percent of all species disappeared. Late Ordivician environments were stressed by the buildup of continental ice sheets during the last few millions of years of the period. Sea level droped as a consequence, and the vast shallow, Ordovician seas dried up, devestating their biota. The ice sheets melted by the end of Ordovician time, however, allowing shallow maring waters once again to flood the continents. Life renewed itself in the early Silurian Period."
"When Life Nearly Died: The Greatest Mass Extinction of all Time" by Michael J. Benton (a detailed account of the great Permian extinction) - "In the Late Ordovician, about 440 mya, further substantial turnovers occurred among marine faunas. This extinction event is the first of the 'big five' mass extinctions. all reef-building animals, as well as many families of brachiopods, echinoderms (sea urchins, sea lilies and starfishes), ostracods (microscopic crustaceans, distantly related to crabs and shrimps) and trilobites died out. These extinctions are associated with evidence for major climatic changes. Tropical-type reefs and their rich faunas lived around the shores of North America and other land masses that then lay around the Equator. Southern continents had, however, drifted over the south pole, and a vast phase of glaciation begon. The ice spread north in all directions, cooling the southern oceans, locking water into the ice and lowering sea levels globally. Polar faunas moved towards the tropics, and warmwater faunas died out as the whole tropical belt disappeared."
This second quote seems to blame the glaciation on the movement of the southern continents over the south pole. I am not sure how the Appalacian could have "triggered" the ice age if it was around the tropics. If it started around the south pole, then perhaps the Appalacians were a secondary contributor. Ah, the fun of science, so many arguments, so little time.