Sediments tell you something about the conditions they were deposited under. In particular, this relates to subtle changes in their chemical make-up, which can give information on chemical changes in seawater from millions or billions of years ago.
We therefore analyse sediments from time periods of rapid climate change to determine how the Earth's climate system responds. We concentrate in particular on the chemical weathering of the continents.
Continental weathering is the Earth's primary natural mechanism for removing carbon dioxide from the atmosphere. Subsequently, it is transported to the oceans and sequestered as carbonate or organic carbon.
The response of weathering to changes in climate (e.g. temperature increase, so weathering increases, removes more carbon from the atmosphere, allowing the climate to cool) may be fundamental to maintaining a habitable planet, but we currently know very little about the precise processes involved, or the timescales in which they operate.
The primary tools we currentuy employ for this research are lithium (Li), magnesium (Mg), and calcium (Ca) isotopes. All are tracers of differnt aspects of chemical weathering processes, as well as the cycling of elements in the oceans
See also: Past Climate Change