Anchored to the Seafloor
00 deg 56'S
Longitude: 91 deg 34W
Wind Direction: SSE
Wind Speed: 20 Knots
Sea State 4
Swell(s) Height: 4-6 Foot
Sea Temperature: 62°F (16.7°C)
Barometric Pressure: 1013.5 MB
Visibility: 12 Nautical Miles
Eggs and potatoes
Bacon, ham and sausage
(Dried cereal is always available in the pantry)
OJ in a bucket
Beef pot pie
Chicken Noodle soup
Leftover pork tenderloin from Tuesday
Mini Oreo cookies
Pasta and 3 kinds of sauce: Alfredo, shrimp and clam
September 14, 2001
by Christina Reed
The submarine rift zone west of Cerro Azul volcano is littered
with pillows, not the soft kind you sleep on: pillow lava.
When it erupts on the seafloor it twists and turns forming
balloon-shaped rocks the size of bowling balls, ovens or even
as large as sofas. Flows of pillow lava pile-up onto each other
creating mounds a few meters to tens of meters tall.
Dragging the dredge over this irregular terrain is a difficult and chancy
business. Still, dredging is a standard tool that marine geologists
use to gather rocks from the deep seafloor. We always
hope to get stuck - a little bit - in order to break off rocks
and catch them in the dredge bag, Dan Fornari says. But
getting really stuck is a big problem. Thats when you
get anchored to the seafloor.
When the dredges teeth dig into seafloor, parts of the lava flow break
off and are collected. But sometimes the lava doesnt let go.
Weve got a bite, Joe Licciardi says. Instead of grinding along
the seafloor the dredge has gotten stuck on a rock ledge or large formation of
The eyes around the computer lab turn to the
tensiometer recorder near the winch control. The needle jumps
across the paper. The tension on the trawl wire rises from 3,000
pounds to 5,000 pounds then 6,000 pounds.
Thats a big bite, Mark Kurz says.
We wait for the tension to slack off, but it continues to rise.
In less then a few seconds it has jumped to 8,000 pounds. We
just started a 1,200-meter-long game of tug-o-war with the
We pay out more trawl wire to relieve some
of the tension. Dan Fornari calls the bridge to reverse the ships direction. We want to give the dredge
plenty of slack so it will drop away from the outcrop, paying out wire and moving
the ship 50 to 100 meters backward usually works.
After a few back-and-forth pulls and releases,
the tension on the trawl wire reaches as high as 19,000 pounds
before the needle jumps back to 3,000 pounds indicating normal
tension. The dredge comes unstuck from the seafloor lava flow
- this time, and we continue up the slope.
Thats as high as Ive ever seen the tension go before, Josh
Curtice says. And thats why we always have someone watching the tensiometer.
Meanwhile, down on the seafloor, we hope that
a nice glassy chunk of pillow lava has dropped into the dredge
bag to add to our fantastic collection of seafloor lava from
the slopes of Galápagos volcanoes.
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