| [Thread Prev] | [Thread Next] | [Thread Index] | [Date Prev] | [Date Next] | [Date Index] |
Thanks for the insights on burrowing and its relation to the K/T boundary problem, Norm. I had read Chuck Savrda's 1993 paper in _Geology_ on how he showed a noncatastrophic origin for the K/T boundary in the U.S. Gulf Coast, based on trace fossil evidence; I'll have to go back and read it again. Is this the paper you referred to or did I miss a more recent one in _Geology_? Incidentally, he's a neighbor of mine (relatively speaking) here in the southeastern U.S., so I also remember talking with him about some of his conclusions before the 1993 paper was published. Apparently his evidence disappointed some people who wanted a tsunamite to be there. A similar form of disappointment happened on a field trip to the K/T boundary in the Pote Quarry of Recife, Brazil, last year (associated with the ISC meeting there). Some of us ichnologists on the field trip found burrows in the "tsunamite" that had been interpreted there (no burrows had been reported before), so a lot of controversy erupted right there at the outcrop about whether it was a catastrophic deposit or not. (The ichnolgists and some other sedimentologists said "not.") It was pretty fun to witness and participate. I had talked briefly with Tony Ekdale about some of his work on the "burrowing problem" but hadn't read the paper in the Copenhagen K/T symposium volume. Fortunately, I'll get to talk with both him and Richard Bromley about it in Denmark next month - the Third International Ichnofabric Workshop will be meeting there. I'm sure it'll be a fun topic for discussion and I'll be glad to share my impressions. Unfortunately (for me!), I'll miss the part of the workshop field trip that visits the K/T boundary at Stevns Klint. Just out of curiousity - how far apart (lithostratigraphically) are the multiple anomalies at Brazos and Braggs? Some burrow systems, such as _Thalassinoides_ or _Ophiomorpha_, have vertical extents of 2-3 meters. Not to be a constant devil's advocate, but I'd like to see more accounting for the effects of bioturbation in the light of such possibilities. Anthony Martin Geosciences Program, Emory University Atlanta, Georgia USA -- /========/ LearnLink: Expanding Educational Horizons !! !! !! Internet/Telnet: bbs.learnlink.emory.edu !! !! !! For information, mail Info@learnlink.emory.edu /========/ "Minds are like parachutes, they must be open to function."
Partial index: