Oxygen-Depletion:

Bubbles in Amber: Richard A. Kerr, Science 238 #4829, 890 (13 November, 1987).

Berner, R.A. and Landis, G.P., 1988, The major gas composition of ancient air: Analysis of gas bubble inclusions in fossil amber. Science, v 239, 1406-1409. (http://www.sciencemag.org)

Berner, R.A. and Landis, G.P., 1987, Chemical analysis of gaseous bubble inclusions in amber: The composition of ancient air? Am Jrnl Sci, v 287, 757-762. (http://www.sciencemag.org)

Landis, G.P. and Berner, R.A., 1988, Is the air in amber ancient? (Response). Science, v 241, 721-724.

Dudley, R. (1998). Atmospheric oxygen, giant Paleozoic insects and the evolution of aerial locomotor performance. Journal of Experimental Biology 201:1043-1050.

Interview with Robert E. Sloan - by Joe Cain -- (see below) http://www.ucl.ac.uk/sts/cain/sloan/1.htm

Dinosaur Breath, by John G. Cramer http://mist.npl.washington.edu/AV/altvw27.html

Transformation - Resin into Amber http://www.gplatt.demon.co.uk/transfor.htm

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http://minerals.cr.usgs.gov/docs/gips/0aii-new.htm

Understanding Our Planet Through Chemistry

A U.S.Geological Survey HTML Poster Session excerpt: Air bubbles, amber, and dinosaurs

Gary Landis - (303) 236-5609 Ages of ice samples found on the Earth cover a span approaching 200,000 years. But how can we tell what the Earth s atmosphere was like before that? Recently, USGS scientists have used a gas QMS to determine the oxygen level of ancient samples of Earth s atmosphere from a most unlikely place amber. The fossilized resin of conifer trees, amber is interesting to scientists as a medium that traps insects, small animals, and plants, preserving them through geologic time for future study. [image] [39k] [151k] Amber -- the fossilized resin of conifer trees -- provides a unique means of protecting intricate samples of the past. This mosquito, lying trapped for 45 million years in a piece of amber, is almost perfectly preserved. The recent extraction by scientists, of ancient DNA from organisms entombed in amber much like in the science-fiction novel and movie, Jurassic Park is an example of why scientists are intensely interested in amber. Minute bubbles of ancient air trapped by successive flows of tree resin during the life of the tree are preserved in the amber. Analyses of the gases in these bubbles show that the earth s atmosphere, 67 million years ago, contained nearly 35 percent oxygen compared to present levels of 21 percent. Results are based upon more than 300 analyses by USGS scientists of Cretaceous, Tertiary, and recent-age amber from 16 world sites. The oldest amber in this study is about 130 million years old. [image] [44k] [155k] This 84-million-year-old air bubble lies trapped in amber (fossilized tree sap). Using a quadrupole mass spectrometer, scientists can learn what the atmosphere was like when the dinosaurs roamed the earth. The consequences of an elevated oxygen level during Cretaceous time are speculative. Did the higher oxygen support the now extinct dinosaurs? Their demise was gradual in the transition from late Cretaceous to early Tertiary times, as was the decrease in oxygen content of the atmosphere. [image] [17k] [51k] This chart shows a major decrease in oxygen content in the atmosphere from 35 percent to the present day level of 21 percent. This decrease occured about the same time that the dinosaurs disappeared -- 65 million years ago. http://minerals.cr.usgs.gov/docs/gips/0aii-new.htm

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COOKBOOK COSMOLOGY - PART II

An Engineering Approach to Tectonic Plate Suffling by Neil B. Christianson

excerpt: Just as an aside, volcanism may also harbor a geochemical oxygen cycle. Gary P. Landis, when he worked for the U.S. Geological Survey, and his colleagues proposed that the dinosaurs died 65 million years ago because of a drop in the atmosphere's oxygen level5. They arrive at their highly controversial conclusion based on analyses of gas bubbles found in amber, a fossilized form of tree resin. Amber bubbles show a sharp drop in the atmosphere's oxygen content at the end of the Cretaceous period, from a high of 35 percent down to 29 percent. They speculate that the oxygen decline, which was caused by a decline in volcanic activity and lowering sea levels, killed the dinosaurs because their lung capacity could not adjust to the reduced oxygen level. http://ftlmagazine.com/features/tectonic.html

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Interview with Robert E. Sloan by Joe Cain

Session 1 excerpt: ....the surrounding environment. And by looking at these things, he came up with a curve in the amount of oxygen with time. He wanted to check this because it seems that the normal view that the oxygen has forever been at where it is right now, at 21 percent of the atmosphere, didn't seem reasonable at all, particularly in view of what [Preston] Cloud had done in the way of Precambrian oxygen concentration. So he did these calculations, and then he looked up an isotope geochemist to see if there were some way that they could literally measure the oxygen concentration at various times in the past. They got some samples of amber from the late Cretaceous, essentially Judithian about 75,000,000 years ago from Saskatchewan and looked at the bubbles of gas inside the amber. There had been a general feeling that amber was too reactive, that this couldn't possibly be air and yet when they took these pieces of amber and crushed them in a vacuum line in screw vice slowly so that they literally could then, as each molecule of gas or blob of gas leaked out of the amber, they would run it through a mass spectrometer and literally measure what the mass distribution was. And you would easily pick the points for nitrogen and the points for oxygen and argon and a few other things, and they found to their very great surprise that they got about 35 percent oxygen in the bubbles, in the amber. Well, it would be relatively easy so everyone thought, to reduce the amount of oxygen in amber by reaction with the resin of the amber. But how would you increase it? Or where would the oxygen come from? So they published a preliminary paper, and of course, they were jumped on. Everyone said that amber was too reactive, couldn't possibly work. So they did a whole series of analyses. They kept one piece of amber, at 10E-19 torr, which is about the same vacuum as in outer space, for three years, and nothing changed. And they put some more amber in a reactor and made argon 39 and then checked to see what the argon 40/39 ratio might be in the gas that came out of the bubbles and surprise, they got Cretaceous values of the argon 40. So the net result was after a lot of effort, Gary Landis, the geochemist who was then working for the USGS of Denver, came up with a couple of papers in which he refuted all the arguments about this. In the meantime, it was interesting to have this one datum point that 75,000,000 years ago there was roughly 35 percent oxygen. What we needed was a lot of data points. And so in 1986 or 1987, one of the things that my class did on our annual Bug Creek camping trip was to literally mine coal beds for amber. And we started with the coals, beginning with the Nul coal just 60 feet under Bug Creek Anthills, and worked all the way up to the highest coals in McCone County. http://www.ucl.ac.uk/sts/cain/sloan/1.htm