Juan de Fuca Ridge Cruise
July 20 - August 1, 2000
Over 650 km (~400 miles) off the Washington-Oregon Coast

July 29: Day #10

A mesopelagic squid we saw during today’s descent into deeper waters.

Log Entry: We all got a good night’s sleep last night, as we were in transit once again. During the night, we traveled back to the southern segment of the cleft where we had been the day before yesterday. Since our deployment of instruments yesterday was a critical dive, we wanted to make sure we would dive while the weather was good and not risk the chance of missing the dive due to rough seas. Although the forecast did not call for any severe conditions, the weather had worsened just enough for us to adjust our dive plans. The instruments have now been deployed, and we awoke this morning back in the southern cleft, ready to dive once again. We traversed over the ridge axis, starting at the far east end, crossing over the east wall of the axial valley, and ended after crossing over the west wall of the axial valley. Again this east-west crossing parallel to the ridge axis offers an opportunity to see many rapidly changing features as you travel: older, encrusted flows outside of the valley, over steep faults and fissures, and finally into younger sheet and pillow flows before leaving the valley. At one point during our journey we came across what appeared to be another low-temperature vent site. Although we did not observe any active venting, the "mound" was covered with a thick yellowish bacterial mat, a sign that there is some venting of hydrothermal fluids. Once again, our pilots were able to obtain a very difficult sample of extremely soft material from the vent area. Pilot Paul Tucker skillfully improvised by using a push-coring tube to scoop up the sample and return it to the core quiver without losing any sample material. The Kraft "Raptor" manipulator arm he used to gather this sample can be seen in the photo below. Another sample which was obtained during this dive was a large pillow "bud", which measures over 30cm (1 foot) across and has been estimated to weigh over 14 kilograms (30+ pounds). This type of sample really displays the versatility of our ROV Tiburon, as it can grab large, heavy samples as well as very fine sediments and delicate scientific instruments which require feather-like touch. Among the strange deep sea creatures who happened into our cameras were a mesopelagic (midwater) squid and a ray who seemed to be pointing the way to the massive flow we were looking for. (see pictures below). Tiburon was in the water for over 12 hours from surface-to-surface, and the samples were organized, labeled, and photographed. After the dive, Dr. Stakes, Dr. Perfit, and Tony Ramirez plotted positions for the wax-coring while Dr. Tivey reviewed his magnetics data (see picture below). We began wax-coring around 7p.m., and stopped at 3a.m. From 3a.m. until around 6a.m. we were again in transit, this time to a more northerly location called "Monolith". Monolith is a large, high-temperature hydrothermal vent which has not been seen since 1994. If all goes as planned, we will be the first people to see this site in over 5 years, and we will be able to document any changes that have taken place. We are not even sure if it is still active, but if so, we will again be face to face with a chimney expelling water that is over 300 degrees Celsius (572 degrees F) !

Although it looks like the remnants of an ancient, under-water civilization, this structure is actually a geological feature called a "skylight" which provides a view into a tube system.

Dr. Stakes, Tony Ramirez, and Dr. Perfit choose the locations for tonight’s wax-coring drops, as Dr. Tivey reviews his magnetics data behind them.

The Kraft manipulator arm maneuvers a soft, sediment-like sample from a low temperature vent into the "quiver" which holds the sediment tubes.

A ray pointing out the massive flow used as a marker horizon throughout the axial valley.

Today's menu

Chilled Fruit
Oatmeal w/ raisins and brown sugar
Eggs to order
Omelets: ham, mushroom, bell pepper, cheese, onion
Hash browns
Creamed beef

Tossed Salad - Fruit salad
Split Pea w/ ham soup
Lasagna w/ or w/o meat
Buffalo Wings w/ dipping sauce

Caesar salad
Split pea w/ ham soup
Roast beef
Mashed potatoes w/ gravy
Stuffed roasted green peppers
Key lime cheesecake

Previous Day           Next Day