Thanks Katrina. It looks good, but from the website, I can't exactly tell how simple or complicated it is. What I mean by "simple" is that it sticks to factors that can be reasonably correlated with each other, such as the increase in atmospheric oxygen around the rise of cyanobacteria, and, for example, if there are any spikes in oxygen or other factors (anaerobic life forms?) before the paleontological record. I'm trying to look at all indicators for the initial presence of life on earth including those which might be considered conjectural (e.g. a spike in O2 before the paleontological evidence, etc.). I was trying to draw this on a restaurant tablecloth the other night, and I wondered, "Why the hell should I bother if someone else has done it?"
To put it another way, what are the earliest indications of life of earth, and what is the evidence for the conclusion? Also, what is the status of the current debate(s) over both, and what are the positions of the scientific establishment and contrary claims--and how long have any such debates been going on? The latest discussions I have turned up on this subject seem to have occurred at about the turn of the last millennium, and I would like to get up to date. Some sources put it at 2700 Ma, others a billion years later, and others (dare I admit I looked at Wikipedia?) just say "Archean," which could push it back even farther.** Do I hear 544 Ma? 2700 Ma? Who'll give me more? References? I also wonder how much different relevant disciplines (paleobiologists, geologists, geochemists, microbiologists, paleoclimatologists, etc.) have been discussing this with each other. WT * Knoll, Andrew H. A New Molecular Window on Early Life. Volume 285, Number 5430 Issue of 13 Aug 1999, pp. 1025 - 1026,1999, Science. http://cas.bellarmine.edu/tietjen/Evolution/a_new_molecular_window_on_early_.htm#note14#note14 ** Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999. <http://en.wikipedia.org/wiki//w/index.php?title=Special:Booksources&isbn=0716728826>ISBN 0-7167-2882-6 p. 297-301 http://en.wikipedia.org/wiki/Archean At 09:02 AM 9/3/2007, you wrote: >Hi Wayne, > >You might find this Correlated History of the Earth poster useful, >though it is not exactly simple... ><http://www.wmnh.com/wmgspub.htm>http://www.wmnh.com/wmgspub.htm > >Cheers, >Katrina >-- >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >Katrina M. Dlugosch, PhD >Postdoctoral Scholar and Lecturer >Ecology and Evolutionary Biology >University of California >Santa Cruz, CA 95064 >tel: 831-459-3677 >fax: 831-459-5353 ><mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED] >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
