Friday, 20 February 2004

Why Go to Papua New Guinea? continued.

Where was I...oh yes, yesterday we talked about why we are in Papua New Guinea and today I promised to begin talking about ways we plan to look below the earth's surface.

Have you ever helped to plant a tree? How would you go about it? Well, first you would probably find a tree to plant and second, decide where you are going to plant it, but the third thing would probably take is a shovel and start digging. When you dig in the ground you start to uncover various things, roots from other trees, perhaps a worm, you may discover a rocky layer below the surface. It is similar to the types of things we might discover here on the ocean floor, but the way scientists on the Melville capture and study the layers of sediment is slightly different than taking a shovel out of the garage.

On this cruise we have brought with us a Jumbo Piston Core that allows us to recover a sample of the sediment layers beneath the sea floor down to approximately 12 meters or 40 feet. The jumbo piston core is lowered into the water on a thick steel wire because of the 4,500 lb weight attached to the top end of the core barrel. Now if you're like me, you might be are asking, "What exactly is a Jumbo Piston Core?" The jumbo piston core has a diameter larger than most piston cores that is why it is called "jumbo." The piston core uses a long tube of steel fitted on the inside with plastic (PVC) core liner. A core cutter located on the end which hits the seafloor first cuts into the surface allowing the forces of speed, weight and gravity to drive the steel pipe into the ground. The piston is a sliding piece that begins in a position just above the core cutter and moves up the core when the core penetrates the seabed. So why use a piston moving up the core? Imagine you are on the edge of a river and you step in the mud. When you pull your foot out, your sneaker gets stuck because of the suction. Well, the same thing happens with a piston core when trying to pull out the core. The piston creates suction in the core and has steel fingers called a core catcher that traps the sediment, keeping it from falling out on the way back to the surface. When this is back on deck, the PVC liner is removed, cut into sections and labeled with information about where in the Gulf the core was taken, which section of the core each piece is and which end is top and which is bottom. Check out today's slide show to see what a jumbo piston core looks like and how the process of taking a core works!

So now, what happens to all of that mud? Perhaps we could sell it to spas for deep-sea mud baths? Not a bad idea, but I'm guessing that's not it. I'll go find out now and let you know tomorrow!

Today's weather and location at 1300 (thirteen hundred hours, military time for 1:00 pm)
Air Temperature: 28°C (82°F)
Water Temperature: 30°C (84°F)
Salinity: 30.78 PSU
Barometric Pressure: 1009.9 mb
Relative Humidity: 83%

Longitude: 8.07123° S
Latitude: 145.04382° E