Methods

Methods

Methods

Dredged rocks are collected by dragging an open steel box with an attached chain bag along the ocean bottom behind a ship. The rocks from the hauls are curated and stored in wooden dredge boxes. Rocks in a dredge haul frequently weigh hundreds of pounds and a single leg of an expedition often collects and returns in excess of 15 tons of material.

The core collection contains cores that were collected using gravity, piston, trigger, vibra- and box-coring techniques. Whole round core sections are then halved and stored in polystyrene D-shaped tubes, labeled and kept on specially designed wire racks. Each whole round produces two halves, one called the working half (the half from which samples are taken) and the other the archive half (the half that remains as a record of the subseafloor in that location).

Sometimes scientists want to get a better look at samples before they take them from the seafloor, so they will commandeer both manned and unmanned submersibles to do so. Scripps Institution of Oceanography just got their own remotely operated vehicle (ROV), but it is common for Scripps scientists, along with scientists worldwide, to use the DSV (Deep Submergence Vehicle) Alvin and/or ROV Jason from Woods Hole Oceanographic Institution (WHOI) to collect rocks, push cores, temperature measurements, and much more using the manipulator arms attached to these vehicles. Manned and unmanned submersibles are also amazing tools due to the high quality and up-close video and images they also collect. And in the case of the manned submersibles, scientists get to travel to the seafloor themselves!

Scientists then use a wide variety of methods to subsample and analyze both the rock samples (i.e. thin sections, isotope analysis, chemical analysis, and more) and working core halves (i.e. smear slides, grain size, x-ray analysis, isotope analysis, carbon dating, and more).