between the legs of the co-pilot, Frank Rosazza, who was sitting in the back trying
to stabilize the instrument by turning the screws with a screw-driver until the three
eye bubbles would be horizontal. This usually took about 10 min and needed to be
done without moving the submersible. This also required that nobody make move
inside the sphere. Once the measurements were finished, I asked the pilot to take a
sample of the rock that I had been looking at through the porthole while I was
immobilized during the 10 min required for the gravity data acquisition. Jean-Paul
was very fast in sampling, it took him only 5 min to grab a piece of the rock, and
then off we went. During our progression on the bottom I was surprised to see so
much volcanic debris in the form of ash and angular rocks suggesting explosive
volcanism. This type of material at 2285–2700 m depth was associated with small
volcanic cones less than a few tens of meters tall. The pillow lava flows that we
encountered were enormous, reaching up to 4 m in diameter, and therefore they
were much larger than those commonly found on spreading ridges. They also
differed from typical spreading ridge pillow lava flows by their smoother surfaces
and a lack of surface corrugation, which suggested that they were of a more fluidal
nature. I called them ‘‘giant flows’’ because of their size and because they extended
up to tens of meters in length down slope. As we climbed up the side of the
volcano (\1900 m depth), there was an increase in the pyroclastic material, which
was a mixture of ash and coarse gravel size debris scattered on top of the giant
pillow lava flows. It was at a depth of less than 1700 m that I noticed hyaloclastite
slabs, and patches of Fe–Mn oxyhydroxide, indicating the presence of hydrothermalism. When we reached a depth 1583 m, we heard an order on the radio
telling us to come back up. Indeed, the time of our dive was over, so the pilot
dropped some ballast and the submersible started to rise. It was now 00:35 GMT
(Greenwich Meridian Time), that is to say 4:35 PM local time, and we had been on
the sea floor for 5 hours. We took our 10th rock sample and made another
gravity station before leaving the sea floor.
Two other dives (PN 02 and -09) took place in continuity to the first one along
the same flank of the Adams volcano. The scientists on board the Nautile were
Colin Devey (from GEOMAR in Kiel) and Klaus Lachschewitz from the University
of Bremen. They were both geochemists and it was the first dive for each of them.
This means that they had to expect to have a ceremony of initiation after their return
on board the ship. Indeed, during this cruise we had the most elaborate ‘initiation
ceremonies’ for First Dives that I have ever seen. This was because we had several
scientists and engineers that had never dived before. The initiation ceremonies were
usually organized by the submarine group, assisted by other experienced divers.
They generally consist in hosing the new diver with water when he comes down the
stairs after getting out from the submarine. The first-time divers are prepared for
what’s going to happen. As soon as they come out of the submersible, they remove
their fire-proof jump suits before coming down the steps. Sometimes the ceremony
became more elaborate when a special mixture of water and other goodies such as
leftover coffee and oil were thrown into a big garbage barrel and the diver was
forced to step inside. In compensation for his discomfort and his patience, the
novice-diver received a nice colorful diploma from the submersible group.
Dives on Adams and Bounty Volcanoes
333
to stabilize the instrument by turning the screws with a screw-driver until the three
eye bubbles would be horizontal. This usually took about 10 min and needed to be
done without moving the submersible. This also required that nobody make move
inside the sphere. Once the measurements were finished, I asked the pilot to take a
sample of the rock that I had been looking at through the porthole while I was
immobilized during the 10 min required for the gravity data acquisition. Jean-Paul
was very fast in sampling, it took him only 5 min to grab a piece of the rock, and
then off we went. During our progression on the bottom I was surprised to see so
much volcanic debris in the form of ash and angular rocks suggesting explosive
volcanism. This type of material at 2285–2700 m depth was associated with small
volcanic cones less than a few tens of meters tall. The pillow lava flows that we
encountered were enormous, reaching up to 4 m in diameter, and therefore they
were much larger than those commonly found on spreading ridges. They also
differed from typical spreading ridge pillow lava flows by their smoother surfaces
and a lack of surface corrugation, which suggested that they were of a more fluidal
nature. I called them ‘‘giant flows’’ because of their size and because they extended
up to tens of meters in length down slope. As we climbed up the side of the
volcano (\1900 m depth), there was an increase in the pyroclastic material, which
was a mixture of ash and coarse gravel size debris scattered on top of the giant
pillow lava flows. It was at a depth of less than 1700 m that I noticed hyaloclastite
slabs, and patches of Fe–Mn oxyhydroxide, indicating the presence of hydrothermalism. When we reached a depth 1583 m, we heard an order on the radio
telling us to come back up. Indeed, the time of our dive was over, so the pilot
dropped some ballast and the submersible started to rise. It was now 00:35 GMT
(Greenwich Meridian Time), that is to say 4:35 PM local time, and we had been on
the sea floor for 5 hours. We took our 10th rock sample and made another
gravity station before leaving the sea floor.
Two other dives (PN 02 and -09) took place in continuity to the first one along
the same flank of the Adams volcano. The scientists on board the Nautile were
Colin Devey (from GEOMAR in Kiel) and Klaus Lachschewitz from the University
of Bremen. They were both geochemists and it was the first dive for each of them.
This means that they had to expect to have a ceremony of initiation after their return
on board the ship. Indeed, during this cruise we had the most elaborate ‘initiation
ceremonies’ for First Dives that I have ever seen. This was because we had several
scientists and engineers that had never dived before. The initiation ceremonies were
usually organized by the submarine group, assisted by other experienced divers.
They generally consist in hosing the new diver with water when he comes down the
stairs after getting out from the submarine. The first-time divers are prepared for
what’s going to happen. As soon as they come out of the submersible, they remove
their fire-proof jump suits before coming down the steps. Sometimes the ceremony
became more elaborate when a special mixture of water and other goodies such as
leftover coffee and oil were thrown into a big garbage barrel and the diver was
forced to step inside. In compensation for his discomfort and his patience, the
novice-diver received a nice colorful diploma from the submersible group.
Dives on Adams and Bounty Volcanoes
333