Mar 26, 2011

The Gravity Corer

This tool allows us to retrieve sediment cores from the ocean floor using a very straightforward method. Consisting of nothing but a large weight (approx. 1 metric ton) attached on top of a long tube, the corer is lowered from the ship into the water using a powerful winch and kilometers of cable. Once it hits the bottom, the weigth drives the corer several meters deep into the sediment, hence the name gravity corer. After the core is retrieved, i.e. raised back up on deck, it gets cut up into 1 meter sections for the ease of handling and transportation. It is now ready for scientifical analysis.

Depending on the local sedimentation rate at the sampling site, several meters of core can correspond to thousands of years of sediment accumulation on the sea floor. Using radiocarbon dating on a number of samples throughout the core, an age-depth relationship is established.

Samples at certain intervals, depending on the desired resolution in time, are studied for microfossil content and geochemical parameters, allowing researchers to reconstruct oceanographic and climatic conditions of the past. This study of past climatic variability contributes to the understanding of our complex climate system and plays a crucial role in making reliable predictions for the future.

In conclusion, despite its apparent simplicity, the use of the gravity corer will provide us with some of the most important information to be obtained during this cruise.

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