Day 22 – An unfortunate turn of events
Breakfast
- Egg scramble
- French toast
- Sausage patties
- Cream o’ wheat
Lunch
- Polish Sausage
- German pancakes
- Salad bar
Dinner
- Rack of lamb
- Broiled salmon
- Wild rice pilaf
- Penne pasta
- Salad bar
Weather
Winds from the south at 6.2 knots
Position
Steaming to the Tasman fracture zone
Sadly, our trip up North was for nought…the weather did not improve by nighttime, and didn’t look like it would get any better by our scheduled time of departure of today at noon. The main problem was that the swell was of a very short period, so the boat was rocking a lot, making a Jason deployment very tricky and dangerous. On top of that, the time it would take to get down to the required depth – 3600 meters – is around 2 hours, and we had little time as it was, so the dive would have been awfully short.
So much for that – at least we weren’t getting tossed around for five more days South of Tasmania. We’re heading back South now though, towards our next destination, the Tasman Fracture Zone. This is a pretty fascinating feature, and results from tectonic action between two plates. Fracture zones occur perpendicular to plate boundaries, as a result of linear motion over a spherical surface. Take, for example, a partially inflated balloon, and cover it in clay. As you inflate the balloon some more, cracks will start occurring in the clay. Another way to think about it is to consider wrapping a piece of paper around a balloon – you will inevitably get folds in the paper, because it it being wrapped around a spherical object. The one thing this model neglects is the fact that the crust of the earth is actually made up of multiple plates, all interacting linearly with each other. But the premise is the same – at the boundary regions, or at the interaction between two plates, the linear motion between them causes these fractures to occur to compensate for the spherical nature of the planet. The Tasman Fracture Zone accounts for much of this compensation between the Antarctic and Australian plates, and extends from just Southwest of Tasmania all the way down close to Antarctica. We’re heading to the northernmost tip of this fracture, which consists of a cliff face with more than 3,000 meters of relief!
What’s more, this face is the first the waters coming from the West have seen for a long long time; we’re hoping that it is rich with corals and other life. We have a relatively small weather window of 36-48 hours, so we’re really going to try to maximize our depth coverage and lengthen the sample collection regimen, maybe up to collections every 200 meters (versus the previous 50 m collections). Our longest dive was 50 hours, and we were able to cover about 700 vertical meters. We’re hoping to cover around 1000 meters in the vertical on this dive, starting around 3800 meters – the deepest we’ve gone yet by over 1000 meters! This should be an exciting dive; there has been little mapping of this area save the bathymetry work of the Southern Surveyor and some other ships; ABE dives were not conducted in this area so we have not much information about the microbathymetry or the flora and fauna. The idea that these waters might carry many unused nutrients leaves the prospect of a flourishing community, although it might be that our solitaries will be outcompeted by other creatures like sponges. However, our corals seem to enjoy high current rates, and are found in great quantities on ledges and outcroppings. So we hopefully will see tons of corals along this steep cliff face!
