Maggie's Farm

There are two places that are loosely connected to post-K/T extinction events: Mt. Toba and the current Yellowstone hot spot. Also the last of the Deccan Traps eruptions, if memory serves.

It is a necessary reminder that the crustal plate movements that started to get going 70-100 MYA started to quickly change global environments: removing the shallow (~1km) deep continental seas changed the entire heat storage system of Earth... as did Antarctica slowly moving into a polar position, which gave the planet a huge heatsink to radiate heat into space. The boloid of 65 MYA chilled the planet down by blocking out sunlight and the heat left the oceans, after that the low residual heat left could be tipped over into glacial periods due to volcanic activity and/or minor solar output variations. Until the plates stop their jaunting around and form up a nice supercontinent or just slow down to let the continents subside to get those lovely inland seas, we are stuck with the freeze thaw cycle of the global thermometer. And that hand that reaches to that are the mega-caldera event volcanoes.

There aren't many of them and they have a long-cycle periodicity... and Yellowstone is overdue... and the caldera has shifted over 3' upwards in the center over the last century. As mankind has never had instruments to record one of these events, we really don't know what its precursors are. This is not a Tambora, Pinatubo, Krakatoa, Thera, Vesuvius or Rainier... those are tiny in comparison to Toba and Yellowstone.

To scale the ash and dust output: consider Mt. St. Helens output to be a sugar cube, then Tambora is a box of sugar cubes you can get at the store... Yellowstone is a crate 3' on a side full of sugar cubes, neatly packed. Tambora gave us the 'year without a summer' and chilly summers for a few years after that. Toba is nasty... Yellowstone is deadly as it goes on century long kicks once it gets started. Out in Washington and Oregon you can see the flood basalt layers that the Snake River and other rivers have cut down through... 10-30' layers of basalt with ash in between... that was laid down when the hot spot of Yellowstone first appeared. Those basalts start at the head of the Snake River Canyon... save for the wide areas that mark where the hot spot erupted... and go out nearly up to Canada and west to the easternmost Cascades. Big flat area out there... a single eruption of Yellowstone has left 10' of ash coverage, in the Gulf of Mexico and 3' out to DC and 1' at Sudbury, Ontario... Toba is Yellowstone's weaker brother.