Linking Earth, Ocean, and Air at the AGU

December's annual fall meeting of the American Geophysical Union presented another opportunity for specialists in everything from air pollution to the origin of Earth to immerse themselves in their narrow disciplines as well as cross into related areas. Overlap between disciplines can be peripheral but interesting, as in the examples below. The amount of salt in surface water can influence ocean circulation and thus climate, and water passing from the crust through sediments into the ocean can help control the concentration and composition of seawater salts.     

Cretaceous, Paleocene, and Pleistocene Sediments from the Indian Ocean

Two deep-sea cores containing Cretaceous, Paleocene, and Pleistocene sediments from an oceanic rise approximately 500 miles southeast of Cape Town contained well-preserved fossil foraminiferal ooze made up of about 97 percent planktonic forms, including species of Guembelina and Hedbergella. High percentages of particles less than 53 micro in diameter in the Cretaceous and Paleocene sediments indicate a deep-water open-ocean depositional environment. These sediments are the oldest recovered so far from the Indian Ocean.