A GLIMPSE OF DEEP TIME - Layered cliffs in Italy tell a story of glacial periods and sea level variations

It’s not often that we get a glimpse of deep time.  But the cliffs at Italy's Punta di Maita on the photo below tell a story of long ago.

 

Each band is a layer of seafloor sediment that accumulated long ago in 21,000-year orbital cycles, and was eventually pushed by tectonic activity into their current formation.

 

They are time made macroscopic — and when microscopic fossils in the layers were analyzed by researchers from Australian National University, they told a climate tale stretching back 5.3 million years.

As described in an April 17 Nature study, the researchers used measurements of oxygen levels in plankton fossils from the Punta di Maiata formations to infer prehistoric water flows through the Straits of Gibraltar, which in turn reflect sea level changes caused by the melting or freezing of glaciers.

The upshot: 5.3 million years of deep-sea temperature trends which extend the deep-sea record by several million years and suggest that the current glacial period began 200,000 years earlier than traditionally thought.

 

That insight aside, the new method could lay a foundation for a more fine-grained understanding of historical climate patterns and their relationship to sea level. As climate change looms, that could prove to be quite useful in our own precarious moment.

Read more and see graphs:
http://www.wired.com/2014/04/deep-sea-temperature-record-grawk/

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