Re: [meteorite-list] Cyclic mass extinction?

[TMS/TNS/HRC]

Hi Edward and List,   I took a course in college called Catastrophes and Mass Extinctions.  Our "textbook" was called "Nemesis the Death Star and Other Theories of Mass Extinction."  As I recall, Nemesis was not one of the more compelling theories, but interesting to contemplate nonetheless.   I will look around for the book and if I can find any more info, I will let you know.   Regards and Good Night from rainy rainy Alaska, Jeannie The Museum Store/The Nature Source IMCA #9236 www.thenaturesource.com   ----- Original Message ----- From: Edward R. Hodges To: [EMAIL PROTECTED] Sent: Wednesday, July 24, 2002 10:58 PM Subject: [meteorite-list] Cyclic mass extinction?     I happened to catch the last few minutes of a show on PBS about extinction. One of the scientist had compiled data on thousands of extinct species and graphed the times of their extinction. In the timeline he created there seemed to be above normal rates of mass extinction every 26 million years. Another scientist is working on a theory that the sun has a companion star, "Nemesis" that perturbs the orbit of comets in the Oort cloud which impact the Earth roughly every 26 million years. Who can shed some light on this topic? Wouldn't there be clear evidence of meteoritic dust fallout in clay deposits in strata spanning every 26my? Interesting, very interesting. Didn't catch the name of the show, or the names of the scientists.- Edward   Edward R. Hodges www.meteoriteonline.com IMCA#4173