
Snow pit in Greenland
We use water isotope (δD and δ18O) data from ice cores to document past climate changes.
We trace changes in atmsopheric chemistry using oxygen isotope (Δ17O) data from reactive nitrogen and sulfur compounds.

Triassic/Jurassic boundary, BC, Canada.
We examine the signature of mass extinction events using carbon isotope (δ13C) data in
sedimentary rocks.
We measure carbon and oxygen isotopes of carbonates and sulfur isotopes from the oldest of rocks.
Old Conglomerate,Greenland
Please visit the Publications section for suggested readings.
What do the symbols δ and Δ mean?
These symbols are the lower case and capital greek letter delta. We use the lower case delta (δ)
to indicate the ratio of heavy to light isotope relative to the same ratio of a standard. For example, the 13C to 12C ratio of some sample material relative to the 13C to 12C ratio
of some internationally recongnized standard. The capital delta (Δ) is used to show to difference of a δ17O sample from the accepted mass dependent value of 0.52*δ18O.