February 27, 2009 | 1
Editor’s Note: University of Southern California geobiologist Katrina Edwards is taking part in a three-week drilling project at the Atlantic’s North Pond—a sediment-filled valley on the ocean floor—designed to locate and study what she calls the “intraterrestrials”: the myriad microbial life-forms living inside Earth’s crust. This is her fourth blog post. To track her research ship’s current position, click here. To see all her posts, see "60 Seconds in North Pond."
STEAMING TOWARD THE NORTH POND (February 20, 2009)—Yesterday, two firsts for me on the ship: Showering while the ship is under steam and doing laundry. Showering while a ship is under steam is something I always find really challenging. It’s hard enough not to slip in the shower under normal conditions, let alone while the shower stall is pitching left and right, and being here on the third deck, particularly so—just couldn’t face it yesterday.
I’m just glad the seas are really about as calm as you can expect for where we are. Then there is the business of figuring out a German washer and dryer. Of course, as part of the safety and information meeting the first day they explained everything—in German. I didn’t even bring a phrase book—what was I thinking?
The Merian has been rocking in the extreme for the past 24 hours. Unbelievably, I’m not sick. Many are though—I’ve seen their faces. I’ve been there, too, and am highly sympathetic. Being sick is the worst.
I’ve seen lots of flying fish but otherwise not much in the way of sea life. I guess that’s to be expected as we’ve entered now the "great blue hole" of the Atlantic—where there is very little in the way of nutrients, and therefore very little "primary production" by the water plants that the rest of the food web in the upper water column depends upon.
You might think that cruises with long transits to the actual experiment site must be a total drag. Actually the opposite is true. First, you have time to acclimate to the sea before being thrown into deck and lab work. Second, you have time to make sure all of your instruments are properly calibrated and working.
Third, and probably most importantly, you have time to talk science with your shipmates and get your plans worked out. Working with a new group on a new program, there’s lots to get straight. Two nights ago, we had our first science meeting after dinner. A digression about dinner, which involved a lovely bottle of red wine: The dining hall is right at sea level. This means that when you are parked and not moving, you can look out the porthole at the horizon. When under steam, it is looking at a front-loading washing machine (see image to the left.)
The science meeting was a series of presentations. I gave the general context for the drilling program, Wolfgang Bach covered the geology and setting for our site, and Heiner Villinger gave the geophysical program overview. I learned yesterday two things about the geophysical surveys: Number one, the data that was collected before was done in the 1980s, not 1970s. Second, the data is apparently lost. So right now we just have one fuzzy picture of North Pond and we do not even have the data used to create it. This is the real problem!
As I explained earlier, much of our site survey work is really as preparation for the next stage—an Integrated Ocean Drilling Program (IODP) project that will take place here in several years (exact timing not known). Our main plans for that are to drill for sediments all the way to the bottom of North Pond—300 meters (1,000 feet) at deepest site—and then 500 meters (1,600 feet) into the volcanic rock underneath, so that we can put instruments and experiments down in them and put CORKs [Circulation Obviation Retrofit Kits] at the top to seal the hole.
I’ll come back to the experiments and measurements another time. But as you might imagine, it is pretty important to make good decisions about exactly where you want to drill a 500-meter hole into the crust. That is at the very heart of what we are doing here—trying to figure out where we should dig our holes. I know, you are probably thinking, how can this possibly matter so much? And why more holes—isn’t there already one there? That is, Hole 395A, the existing CORKed hole drilled in the mid 1970s? It is true, there is a hole there already. But there is a very good reason for wanting a new hole—or two—in the volcanic rock.
I have talked about how seawater is flowing through the volcanic basement rock—it turns out we have some reasonable ideas about how the water is flowing underneath North Pond. I mentioned before that when Hole 395A was made, it started sucking water like crazy. This is because it is near the rock outcrops, on the southwestern side of the pond, where seawater is naturally flowing into the crust. Hole 395A just created a new conduit—like adding a new lane to an old highway.
I also talked about the fundamental truth that, if water is going in, water must be coming out somewhere—the ocean floor is not a net sink for seawater. We’d be in big trouble if it was! The ocean would literally go down the drain. When scientists previously studied North Pond in the 1970s and 1980s, they learned by measuring the temperatures in the sediments all across the pond, that there were a few "warm spots". These are possible areas where water may be coming out. They are warm because the water gets heated geothermally while flowing underneath North Pond, and when it comes out it locally warms the surrounding sediments.
That’s essentially what we want for the next hole—to be placed near where water is coming out. That way, we have an inflow laboratory and an outflow laboratory, for studying the superhighway of water that flows below the bottom of the ocean.
Tomorrow we’ll be coring our first station. I’m excited and anxious at the same time. Still so much to do!
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