Actually, meteor showers occur when the Earth crosses a comet's path and so occur annually, regardless of the period of the comet. I do not have the information handy for checking the periods of shower-associated comets.
The definition of new comets explains why the period is linked to the time of the explosion. Thanks for clarifying that. The evidence for major interval of impacts and extinction at 3.2 million is rather weak, however.
Dr. David Campbell
"Old Seashells"
Biology Department
Saint Mary's College of Maryland
18952 E. Fisher Road
St. Mary's City, MD 20686-3001 USA
dcampbell@osprey.smcm.edu, 301 862-0372 Fax: 301 862-0996
"Mollusks murmured 'Morning!'. And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!
This archive was generated by hypermail 2b29 : Wed Jan 17 2001 - 13:17:34 EST