Breakthrough made in dating of the geological record

Sedimentary cycles reflect climatic oscillations that are ultimately controlled by the Earth's orbital cycles. Therefore, sedimentary cycles can be used to construct astronomical timescales. Using this method, astronomical timescales have been established for the last 12 million years that are more acurate and have a much higher resolution than previous geological timescales. Such timescales are fundamental to an increasing number of applications in many disciplines of Earth science. Researchers are now working to extend the astronomical timescale to earlier time intervals and establish similar time-scales for the continental record.

Time is an indispensable tool for Earth scientists striving to understand all kinds of processes and determine rates of change. More than a century ago, just before the invention of radiometric dating, G.K. Gilbert realized that astronomically forced cyclicity in marine sedimentary archives can be used to estimate the duration of parts of the geological record. His estimates suggested that our planet was much older than the 100 million years (or even 20 m.y., by some accounts) that had been calculated by a thermodynamic cooling model of the Earth.