March 13, 2001 to June 2, 2001
Monterey to Hawaii and back
May 10, 2001: Leg 4; Day 2
Nancy Jacobsen-Stout writes: Day 2. Another long day. The vehicle was recovered from our second dive (11 hours long) of the cruise just after dinner. The Kraft manipulator arm is still not functioning exactly as it should, but the dive was nevertheless very successful with over 30 rocks, a scoop bag, a few push core sediment samples, and several animals for the Monterey Bay Aquarium collected. During the final portion of today's dive, Kelsey successfully completed heat flow probe testing, which included monitoring software performance and the devices ability to penetrate the sediments on the sea floor. Shortly after the ROV was recovered, night operations commenced and by 9:30 p.m. the ships' crew had already recovered the first gravity core. The first one apparently bounced off the bottom and returned with no sample material. An additional gravity core is now being attempted. Tomorrow we move further north west for three consecutive days of diving above Niihau.
The trades continue to blow at 25-30 knots, but despite the less-than-ideal conditions everyone is doing well and working productively. Doug is taking a well deserved break from chef duties during this leg, but remains busy with ship and ROV operations. We're not going hungry though ... the new cook, Derek, has been making great meals for us. All of the ship and ROV crew members, of course, are very helpful and hardworking.
Dave Clague writes: We dove on a string of volcanic cones off the south shore of Kauai today. These cones are related to the Koloa Volcanics on the island of Kauai. The rejuvenated stage of volcanism occurs long after the main volcano has been built and erosion has cut canyons into the volcano. The Koloa Volcanics erupted between about 3.65 and 0.50 million years ago, whereas the main shield volcano was built more than 5 million years ago. Many of the cones near the south shore at Poipu Beach are about 1.2 million years old and the submarine cones we visited may well have erupted about the same time. Each of the cones is composed mainly of steeply dipping bedded volcaniclastic rocks, and volcanic sandstones that originally consisted mostly of volcanic glass are the most common. Some lava flows were observed and some recovered samples have glassy rinds, suggesting they are younger than the samples recovered yesterday from similar cones in the channel between Oahu and Kauai. The lava flows are mainly sheet-like flows although some pillows were observed as well. The top of the final, shallowest cone was covered with sediment that turned out to be black volcanic sand with a veneer of light foraminifera ooze. We also collected a number of sediment samples of gravels derived from the volcaniclastic rocks; such samples have commonly recovered volcanic glass in the past and we are hopeful that these will yield glass as well. The 31 rock samples are all significantly less altered than the samples collected yesterday and will be more suitable for many geochemical studies. At the end of the dive we successfully tested the heat flow probe in preparation for dives scheduled late in the cruise, north of Oahu.
The dive today was almost entirely on hard substrate that hosted a wide array of animals, mainly gorgonians and sponges, but also anemones, crinoids, stars, crabs, shrimps, and sea urchins. Several stars and an Anthomastus (mushroom coral) were collected for Ed Seidel from the Monterey Bay Aquarium.
After the dive we took two gravity cores in areas with low backscatter that we have interpreted to be sediment covered. We are now steaming slowly to the northwest of Niihau Island, where we will dive on more rejuvenated stage cones. The Niihau work was nearly cancelled when we received a telex advising us that the area was closed to ships due to missile launches from Barking Sands Missile Range on Kauai. However, after checking with the base, we learned that no launches are scheduled for Friday, Saturday, or Sunday - the three days we plan to work in the area - but that they would resume launches on Monday. Now all we need is for the wind and seas to cooperate so we can dive there tomorrow!