geologyMcAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams

Home » Historical Geology » Amber and Atmospheric Chemistry

Amber Yields Clues to the History of Oxygen in Earth's Atmosphere

Gas bubbles trapped in amber show an oxygen-rich Cretaceous atmosphere


Republished from a information release posted by USGS in June, 2009.


Compositional History of Earth's Atmosphere



Ages of ice samples found on the Earth cover a span approaching 200,000 years. Gas bubbles trapped in that ice can be used to learn about the composition of Earth's atmosphere at the time they were trapped in the ice. 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.

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.


The Oxygen-Rich Cretaceous Atmosphere



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.


Significance of Cretaceous Oxygen Levels?



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.


Air bubble trapped in amber
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. USGS image.


Citations



Landis, G.P., Rigby, J.K.,Jr., Sloan, R.E., Hengst, R.A., and Snee, L.W., 1996, Pelé Hypothesis: Ancient atmospheres and geologic-geochemical controls on evolution, survival, and extinction, in G. Keller and N. MacLeod, eds., Cretaceous-Tertiary Mass Extinctions. Biotic and Environmental Changes, W.W. Norton, pp. 519-556.

Landis, G.P., and Snee, L.W., 1991, 40Ar/39Ar Systematics and argon diffusion in Amber; implications for ancient earth atmospheres: in Kump, L.R., Kasting, J.F., Robinson, J.M., Atmospheric oxygen variation through geologic time. Global and Planetary Change. v. 5, p.63-67.



Find it on Geology.com




More from Geology.com


Novarupta
Wrong Volcano! The most powerful eruption of the 20th century was misidentified?
hurricane names
How Are Hurricanes Named? Names are assigned as tropical storms are discovered.
Download Google Earth Free
Free Google Earth software allows you to browse seamless world satellite images. Free.
Sliding Rocks
Sliding Rocks Mystery: What causes these rocks to slide across a Death Valley playa?
US Diamond Mines
US Diamond Mines: Did you know that diamonds can be found in the United States?
Diamonds
Diamonds: Learn about the properties of diamond, its many uses and diamond discoveries.
Minerals
Minerals: Information about ore minerals, gem materials and rock-forming minerals.
Fluorescent Minerals
Fluorescent Minerals glow with spectacular colors under ultraviolet light.


Mosquito trapped in amber
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. USGS image.




Oxygen levels over time
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. USGS image.


Mount Rainier Volcanic Hazards
Blood Diamonds
East Africa Rift
Rare Earth Elements
What is Geology?
San Andreas Fault
Teaching Plate Tectonics with Drawings
Diamonds Don't Form From Coal



© 2005-2014 Geology.com. All Rights Reserved.
Images, code and content of this website are property of Geology.com. Use without permission is prohibited. Pages on this site are protected by Copyscape.