JC36: Geology & biology of the Whittard Canyon


Cruise diary

26 June 2009
Location: NE Atlantic, 48° 18’ N 10° 49’W

Natalie writes:

So, apparently there are jobs where it’s normal to be cutting up a 7-and-a-half-metre tube of mud, on the deck of a ship, at 4 O’clock on a Friday morning. Yesterday, that’s exactly what I found myself doing. We’d just used one of the massive piston cores, and now it was on deck, ready to be divided into “bitesized chunks” (about 1.5m long sections) for Jess, to examine, analyze, and generally investigate the mysteries within!

Just in case you, like me, have never found yourself face-to-face with one of these enormous tubes of mud before, let me explain how it works:

The huge piston core (photo, below left) is connected via a trigger arm, and length of cable, to a much smaller ‘trigger’ core. The trigger core hits the seabed first (and does a little coring of its own) this slackens the supporting cable and -you couldn’t see this one coming- triggers the larger piston core into freefall to the seabed (the distance of freefall is determined by a ‘spare’ loop of cable attached to the corer, the length of which is calculated by our general technical man-in-the-know - Jez).

When the piston core reaches the seafloor, the internal piston sits on the seabed, and acts as a stabilizer for the sediment column below. The outer casing passes over the layers of sediment, hopefully without disturbing the structures within. It’s these features that Jess studies, to work out the history of flows, slides and general sediment deposition on the seafloor.

Rigging the piston corer up at midnight.

A slice of the core, and all the ladies – mud is fun!

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