Cruise diary

Monday 28th July 2003

Dave writes...

"Last night Rex and I watched "The Scorpion King" and I must say that it is below standard and to avoid it at all costs!

When I got up this morning I strutted into the lab with my usual suave swagger and was greeted by a very excited Bram. The reason he was so excited is because we think that we have found a mullion ridge. It is a bit difficult to explain but here goes... The mantle is made of semi-molten peridotite. If the spreading of a ridge segment is slow and the mantle is relatively cool then as the ocean floor moves apart, the mantle does not melt. The extension of the crust exhumes the mantle so you get pristine, cool, solid mantle preserved on the sea floor in big ridges. Mullion ridges are extremely rare and is quite a new thing to science so if we can get some samples of it then we have done well!!! We only found this feature this morning. As I write this message we are sending down the dredge. It has already been named as Rourke's Drift after Liz, the computer chapess's, late father. Any further developments and I will keep you posted.

Ahhhahahaha! We have success. The team are very pleased with themselves after we had an excellent dredge. The rocks we brought up from the depths of Rourke’s Drift are very exotic indeed. We have dunites, tectonised layered gabbros, volcanoclastic breccias and everything in between. The significance of the dredge is as Bram puts it "we have dredged through the lower crust past the Moho* and into the mantle!" which doesn’t happen every day. It will be very interesting to see about their geochemical make-up because the samples are extremely fresh which is also very unusual. Rourke’s Drift has been upgraded in size to mega-mullion. There is a lot of work to be done on the samples.

[*Moho is short for the Mohorovicic Discontinuity, which is the boundary between the lithosphere and the mantle asthenosphere as defined by a change in seismic velocity].

On the morning watch Rex had an unfortunate accident with one of the chairs. As the boat rolled violently he fell off it backwards and cracked his bonce on a table, but he was unharmed. The chair, however, was irreparably smashed. Tina was on hand to provide first aid..."

Tina writes...

"When we hauled the dredge in last night, the weather was 'moderate' with a big sea swell. So we got soaked about halfway through (we used to worry about this…now we just laugh and get wet). Once you get wet, you can't get any wetter. Bram (who was waiting to see if his theory about sampling purest mantle was correct) was on hand to record the magic moments. At a dry distance of course.

Before: me, Rex, Bob and Dave.

After: wet feet

The happy news was that the haul was everything Bram hoped it would be, evidence for a mega-mullion ridge (with low, medium and high temperature mantle deformation). The most dramatic rock (for me) was the sheared, foliated gabbro, with a beautiful snakeskin look to the rock, caused by partial melting and shearing across the magma chamber.

Haul of beautiful mantle and lower ocean crust collection: this will be someone’s prized PhD project one day.

The new hobby of knot-tying continues to fascinate, and now we can all survive a fall from a mountain using only our wits, a rope, and how to tie a bowline in a crisis. Andy demonstrates...

Andy also had an exciting time when a wave sprayed over the aft deck, jumping back into the main lab and knocking over a mug. Sadly, he chose the only mug in the place that was privately owned (the others are galley issue). This was my souvenir Darwin mug…he kindly bought me another one.

This was the only bad luck at Waypoint 13

The Master (Keith) and Chief Officer (Phil) on the bridge.

Sophie once again triumphed this morning on the 4-8am night watch, beating Andy, Rex and Dave at cards. Since they were unhappy losers, Sophie kindly posted a record of the scores on to the PC. I tried playing chess with Robin at 5am and lost in a matter of minutes.

These are the small pastimes that keep us sane as we travel in heavy seas between waypoints. It was uncomfortable last night, and harder to sleep, with the feeling of being lifted out of bed and then pushed back in, as each swell rolls the ship slightly on her axis. As I put my contact lenses in this morning, I reached for the saline solution, and the bottle moved a foot away from me without falling over. Rex was less fortunate: he leant back on his chair and kept going, and now the chair is in two pieces (Rex is still in the one piece and none the worse for the experience).

Life on the bridge matches our 4-hour watch changes, with an officer in charge and a lookout posted. Everything is computerised, and once course changes are made, they are carried by an autopilot. Any corrections required are fed into the computer and calculated automatically. The course is plotted as a dashed line, showing where we have come from and where we are going to. Weather reports are printed out regularly, along with reports of any current pirate activity (pirates are common in some areas, where they take over a boat for what she’s carrying. The area we are in is not known for piracy). We are also flying symbols that tell other ships we are carrying out scientific activities, so unless the pirates are after a selection of interesting geological specimens, they probably won’t want us.

Last night’s dredge brought up some more interesting rocks, and now we are nearly at the next waypoint. And it’s time for me to go back to bed..."

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