Study Links Extinction Cycles to Changes in Earth’s Orbit and Tilt (Not man made global warming?)

NY Times ^ | October 12, 2006 | JOHN NOBLE WILFORD

[gleeaikin]

"Milankovitch Cycles"

Recently read that MC's had been disproved as a major cause. Other possible causes are major meteor/asteroid (boloid) strikes, such as one that may have caused the great Permian extinction, the one that killed off the dinosaurs, and the Chesapeake Meteor 34 million years ago (mya) which left a crater 50 miles in diameter in the lower Chesapeake Bay.

Then, of course, there are the volcanic events, including Yellowstone (roughly every 600,000 years), Long Valley (700,000 years ago), Toba 74 thousand years ago leaving a crater 18 by 65 miles, which nearly destroyed human kind.

Significantly smaller events of this type cause lesser death tolls, but still noticeable on specific species.

So much to learn, so little time.