Something about Amber!

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.

This was made by Geology.com