March 13, 2001 to June 2, 2001
Monterey to Hawaii and back
April 3, 2001: Leg 2; Day 3
Dave Clague writes: The strong currents and high winds that had made last night's vehicle recovery a bit too exciting abated during the evening and we completed 5 gravity cores overnight, although only two recovered sediment. It appears that the sediments in this region are generally too sandy and too stiff for successful coring. In the morning we decided to reverse the sequence of two dives planned for the day to address the highest priority work first, just in case the sea conditions deteriorated again in the afternoon. The first dive was on the -400 m reef (the 130 thousand year old one), to examine the reef face and a series of karst-like, nearly circular depressions behind the reef. Karst forms where fresh water dissolves the reef carbonate, and the depressions on this reef have a shape similar to those that form when reefs are uplifted above sea level.
Near the base of the reef face, a small area was covered with basalt fragments, which we (foolishly, it turned out) drove by in hopes of finding their lava flow source farther uphill. That was the last basalt we saw all day! The lower two thirds of the reef face was covered with talus. The upper third was a near-vertical cliff more than 50 meters high, made of carbonate rock. Darker-colored coral fragments could be seen in some places and many places had cylindrical pieces exposed by either dissolution or bioerosion. We collected a number of these, thinking they were likely to be corals. We had hoped to use these to determine the growth history of the reef, by dating them with uranium and thorium isotopes. However, most of the pieces instead turned out to be fragments of coralline algae.
The relatively flat top of the reef has small steps and rolling low hills. Towards shore, the reef top gives way to sediment covered terrain with patch reefs poking through the sediment, and those karst-like features that we wanted to see. The carbonate surrounding the karst-like depressions has crude bedding that dips into the depressions, suggesting that the rims are features produced by reef growth rather than dissolution. These depressions are nearly circular and as deep as 65 m below the reef top. They also have patch reefs that grew as high as 4 meters up from their floors. We hope to use the observations to ground-truth the bathymetric and backscatter maps and thereby convert them to maps of the distribution of different types of materials that make up the reefs.
We ended the dive with 28 samples of carbonate and some push cores. We also tested the vibra-corer again and recovered a short core that bottomed in hard sandy sediment. We also discovered a deep sea geologist -- a small octopus collecting rocks to hide under! The vehicle was recovered at about 3 pm in increasingly strong surface currents and moderate trade wind conditions and headed to the second dive site.
When we arrived at the second site, the surface currents had increased to over 2 knots and we could not launch in such conditions. After a brief moment to modify the plans again, we headed to our shallowest dive site on the -150 meter deep reef, within swimming distance of Kawaihai on the Kona coast. This site is well protected from the wind and, it turned out, did not have the strong currents experienced offshore. We completed a short dive that will be used to compare the structures and erosional histories of the reefs of different ages. Most of the samples collected were covered with red algae and living animals. They should smell really bad in a short time!
Memoirs from a Geologist to Be (helpful for all of the non-scientists) - Kristen Benchley
Since joining the Hawaii cruise on March 31, 2001 there has not been a dull moment or a moment to spare. Here are some highlights since I have boarded Western Flyer. I’ll start with the brief description of Western Flyer; it would make the best cruise for computer/ technical junkies. There are high tech machines everywhere. But even for the less technically inclined person it is a very impressive vessel. There are TV/VCR’s in every room, yes every room (even on deck and in our "staterooms"). On of the most impressive rooms is the control room for ROV Tiburon, it is straight out of a sci-fi film. And it is even equipped with four first class airline seats for the "peanut gallery". Today I counted the video screens that comprise a twenty foot wall ---30! There are 30 screens that are monitored during each dive, not by one lucky person but a whole science/engineering crew. Red lighting sets a mellow mood in the room. It’s a "retro" feel and matches the choice of music, which has mostly been Classic Rock. Back to the videos…the cameras carried by Tiburon are used in the selection of which rock/ dirt samples does the chief scientist want? This can be a tough selection. Juli and I usually suggest the smallest rock because cutting a rock that is greater than football size can be difficult. This brings me to the daily chore of cutting rocks. Don’t worry it is not as dangerous as it sounds. It’s actually quite fun. We have our own saw (see photo from April 2) that can cut any rock into smaller pieces, but actually does not cut through wood that well. Before you make your first slice, you must decide which area of the rock sample will yield the best thin-section and is not too difficult to cut. What is a thin-section you ask? To really study a rock, a very thin slice or section is glued to a microscope slide and then ground down until it is even thinner. With that you can then view the thin section through a microscope, which allows scientists to identify specific minerals and loads of other properties of that rock sample. Among the fun jobs that I am doing, I have helped wash, sketch, and photograph the rock samples after the faithful Tiburon returns from the depths of the Pacific. The samples that were recovered tonight had especially interesting inhabitants that were actually once living. Jenny and Kyra took special interest in the precious coral. They placed the little critters (in between their sad sobs, because of course the coral died) in bags and froze them for later analysis by biologists back on the mainland.
A few things about daily functions on board. To start, the food is great and I don’t have to cook. Three cheers for the chef Doug Alexander! This is a good time to mention the crew. All of them are doing a wonderful job. Whoever would sit in a 65° C (150° F) engine room for any length of time is a very dedicated employee. But they do get to play (operate) a lot of cool machinery. I’m a little jealous. Not that washing rocks that have been collected from a depth of 1000 meters isn’t cool. Being out to sea has not prevented anyone (except for me) from working out. On board there is a Stairmaster, two bikes, and a bow flex (and Kyra’s jump rope and mat for sit-ups). Today was an especially beautiful day, the sun was shining!!! Which led to a spectacular sunset with the infamous "green flash". There is a very lively group on board as you can see. You could consider Western Flyer the vessel that doesn’t sleep (or better yet, does not stop thinking).
Cheers! (This is a traditional closing used by Geologists)