Transcript of Bill Ryan (Port Observer)
This is based on real-time audio recordings of port hole observations
and subsequently modified and richly supplemented by a review
of all of the videotape.
_______________
10:06 2717 261 Landed on the bottom. At last the stirred-up
sediment cloud clears. The terrain around is heavily sedimented
pillow lavas with depressions between the pillow heads completely
covered in mud, and the spaces between the protrusions are all
interconnected. Age 3.0 of Ken Macdonald.
10:07 2716 290 Underway to Way Point 2. Elongated pillow lavas
are everywhere.
10:08 2714 286 Briefly stopped to set clock for display on video
cameras. Could not make it precise. The settings were left with
the display showing a time about 30 seconds earlier than the time
logged in the computer. [These notes are all in computer time
that registers with the subs navigation].
10:09 2715 286 Massive elongated pillow lavas trend downslope
in the east direction. All pockets between pillows are joined
by sediment. Pillows are studded with intact, yet long, delicate
and fragile-looking digits.
10:11 2709 286 Climbing a slope over elongated pillows (what will
subsequently be called tubes) with a 6-1 (length-diameter) aspect
ratio all trending down the apparent slope. No visible tectonic
disruption. Gorgonian coral.
10:12 2704 286 Continuing to climb the slope with elongated pillows
and lava tubes trending down slope.
10:13 2700 288 Elongated pillows.
10:14 2696 296 Bulbous tall pillows with striations, cooling cracks
and a few with open trap doors in crest. Coiled pillow heads are
typically bent over in the downslope direction.
10:16 2685 294 Terrain is dominated by hummocky pillow lavas,
heavily sedimented, 90-100% sediment cover.
10:17 2680 294 Another Gorgonian stalked coral in a terrain of
pillow tubes, some tubes up to 10 meters in length and set on
the landscape among a few detached pillow heads.
10:18 2674 295 Long pillow tubes erupting everywhere from this
slope
10:19 2669 296 Crossing a 3m deep fissure running approx. N-S
and cut through the pillow lavas in a slight zig-zag pattern as
if finding the place of least resistance.
10:20 2671 296 After descending a small 2m step we continue up
the constructional volcanic slope through more pillow lavas, observing
some broken and scattered digits. Pillows still dominantly elongated.
A 3 meter long tube has extruded from a pillow stump.
10:21 2666 295 Stopping for Rock Sample Station 1. Heavy
sediment cover indicates a substrate of at least Age 2.5.
Sediment is distinctly brown to umber in color suggesting an important
and perhaps dominant component of hydrothermal products.
10:30 2664 291 Back underway and climbing through terrain of elongated
pillows and tubes, we have not yet observed any lobate lava morphologies.
10:32 2661 292 Tiny shrimp with a red stripe behind its head swimming
in the water. Crossing a small west-facing escarpment and then
approaching first lobates of the dive with a small 1m diameter
collapse pit in their roof. The roof rock of several of the lobate
flows here is cracked into tabular slabs but mostly it is uncollapsed.
10:34 2660 294 The steepness of the slope we are climbing has
substantially decreased and we observed more collapse roofs of
lobate type lavas. Some signs of scattered angular talus.
10:35 2661 292 Bottom falling away into a 6 meter deep fissure,
talus on its floor, bedrock layering seen in wall facing us and
consisting of round truncated pillow shafts (trunks) and lens-like
cross-sections of lobate flows.
10:36 2658 294 Looking over the edge of a west-facing cliff down
7-8 meters onto a floor strewn with talus. Horizontally bedded
lavas are exposed in this wall with thicknesses on the <1m
scale. Suspect that this cliff is a eastwardmost bounding fault
of the east wall of the rift valley ahead.
10:37 2657 296 Heavily sedimented lava terrain, although the thickness
of the cover on the talus is less than that observed on
the intact lavas. The talus is estimated as age 1.5 compared
to age 2.5 for the intact lavas.
1038 2658 296 The floor is 8 meters below us on the altimeter.
The down-looking low-light-level SIT camera reveals pillows elongated
to the east. Bottom coming up as the sub continues in the NW direction.
Pillows below are distinctly elongated.
10:39 2653 297 Arriving at the top of another west-facing escarpment.
The wall is vertical and one can not see to its base. As the sub
drives at a level depth ahead into the water column, the altimeter
climbs to 15.7 meters. When bottom below comes into view it continues
to shallow. When I looked back at the scarp, it seemed that the
lavas at the very top had dripped down the cliff. The starboard
observer, when queried, replied that he had the same impression.
10:41 2656 271 As the bottom continues to climbs upward it reveals
a surface of pillows and lobates. It is the east-dipping constructional
slope of the top of a sliver of crust that has down-dropped along
the wall we have just passed over. The pillows on this surface
look a little shattered and loose.
10:42 2649 292 Crossing an escarpment (fault?) with the bottom
falling away to 15 m below us on the altimeter. Talus is abundant
in the distal view below.
10:43 2648 305 Reach the far side and cross a heavily sedimented
terrain of age 2.5 cut by narrow (<1m wide) fissures
perpendicular to sub's track. Landscape is dominated by pillow
lavas. This is apparently the top of another down-dropped (?)
sliver. Then further along track the pillow lavas transition into
lobate flows. The lobates look stratigraphically younger by an
observed onlapping against the pillows.
10:44 2651 303 As the sub flies at a near constant depth the floor
below once again shallows to reveal more thin fissures in these
lobate flows and some angular slab-like talus (loose roof rock
?). The terrain has the distinct impression of less sediment than
before and is assigned age 1.5.
10:45 2651 304 Lobate flows predominate
10:46 2647 305 Cross another escarpment, this one 12 meters high
on the altimeter . The smooth lobate extends right to the rim
where it is truncated by the presumed fault that created this
relief. Another slope faces us at a distance of 50 yards on the
CTFM sonar monitor. We slowly motor down and ahead with the bottom
out of sight below us. Looking back I see a bench on the west-facing
wall that we crossed with the same lobate terrain of the rim of
the fissure. It looks like evidence of a thin slice dropped into
the large fissure.
10:50 2649 305 While the sub has motored ahead and descended 2
meters, the floor below has ascended to come into view at an altitude
of 4 meters. It is an east-dipping surface of sedimented lobate
flows and some scattered tabular talus. We cross a fissure in
this surface, this one about 5 m deep whose floor is littered
with angular (blocky) talus. Much less sediment on the talus down
in the crack than on the rims of the fissure. Among the tabular
fragments are the broken trunks and heads of pillows presumably
detached and fallen from some nearby escarpment.
10:51 2654 302 Talus and broken pillows come into view suggesting
a cliff facing us from ahead.
10:53 2645 270 Looking now directly at this cliff in front of
us. According to the dive map it appears to be the west wall of
the rift valley. The base of the cliff is littered with talus
as we climb and look down. As we slowly climb, we view outcrops
of pillows in what appear to be beds or layers more or less horizontal
in extent in the cliff face. Looking into the truncated strata
one sees the radial cracking of the pillow trunks and tubes more
or less circular in cross-section. The altimeter in the stern
of the sub shows 13 meters to the top of the talus ramp as the
manipulator arm picks at the lava from the outcrop at the wall.
We stop to take a sample of this pillow lava at what we judge
from our limited perspective to be the top of the wall. Rock
sampling station 2.
10:57 2646 252 Backing off the cliff and turning around to motor
NE to Way Point 3. Begin to gradually descend looking ahead into
water.
11:00 2648 081 Having dropped only 2 meters we are still up in
the water column at an altitude of 5 m and out of sight of the
lavas below us..
11:01 2654 082 Bottom comes into view ahead of us at last. We
see cracked pillows with the walls of the 5-10 cm. wide cracks
stained white, presumably by hydrothermal fluids. The staining
is not on the sediment right at the lip of the crack suggesting
that the escaping fluids coated the walls of the cracks prior
to the accumulation of the present sediment covering. Some angular
talus lies scattered on these pillows, probably derived from the
nearby west wall of the valley.
11:02 2654 081 Heading east we climb a small escarpment with truncated
pillow lava bedrock exposed in the wall facing us. This ridge
turned out to be the north tip of a spur (north plunging crustal
sliver?) as the bottom falls away on its other side.
11:03 2652 79 Pillow lavas and lobate morphologies on the floor
below us as we cruise briefly at an altitude of 6 to 7 meters.
11:04 2656 080 Cross a narrow <1m wide fissure with talus on
its floor. Climbing a talus slop, consisting mostly of truncated
pillows.
11:05 2651 080 Up and over a ridge with about 4 meters of relief,
heavily sedimented (age 2.5) and consisting of pillows
and lobates.
11:06 2651 080 Crossing N-S fissures in the lobated lava flows.
11:07 2652 079 Crossing two more small fissures in these lobates
as the seabed deepens in one meter steps with each fissure. Outcrop
of thin layers visible in the observable wall of the fissures.
In the outcrop the layers are capped by pillows and lobates right
at the level of the seabed beyond the fissure.
11:08 2649 081 Stopping sub to investigate this outcrop. At close
inspection the thin layers are the filling of 1 and 2 meter diameter
giant tubes whose own enclosing wall (skin) is clearly visible
and less than ~10 cm. thick. The tubes are not perfectly round
in cross section, but one is squashed vertically and the other
a few meters adjacent to it horizontally. The tubes have interbedded
pillow lavas between them and below them a mass of pillow lavas
is seen in round cross-sections.The truncated pillows are but
40-60 cm. in diameter and many smaller than that. The top of the
tubes lies just 20-30 cm. below the seafloor in the wall having
been capped by the surface lobate lavas. One of these surficial
lobates appears to spill a 30 cm. long tongue down the exposed
face of the fissure, but this could possibly be an illusion.
11:10 2647 145 As the sub turns to further inspect this wall another
cross-section of a giant tube appears that is only about 3/4 filled
with the thin (1-2 cm. thick) horizontal (sheet-like) flows and
the upper 1/4 of the cross-section of the tube is a void. It looks
like an incompletely filled sewer pipe. Then another one of the
giant tubes in cross-section comes into view filled with some
thin bedded flows that have run through it and are themselves
submerged under a layer of welded talus that looks like roof rock
perhaps collapsed further upstream into the tube and transported
by the topmost thin flow to the site of this cross-section. This
tube is about 1.5 m in diameter and also lies only one or two
pillow thicknesses below the present seafloor at the top of the
wall.
11:12 2645 082 Underway on the original eastward course from this
brief deviation as the cliff ahead is scaled. Lots of pillow rubble
below at the foot of the exposure. Clearly this wall is bedrock
outcrop produced by some significant vertical displacement of
the seafloor.
11:14 2649 083 Cross a 14m deep fissure or down-dropped sliver(in
a relative sense). The rims of this depression pillow lavas. Talus
is very faint in the SIT camera that looks into the trough. This
cleft (?) appears to run N-S up the rift valley.
11:18 2663 081 Lobates now dominate the substrate. A fissure right
ahead of us gives an excellent opportunity to look again at a
vertical cross-section into the valley floor and two more giant
tubes are exposed, one whose interior is completely filled with
welded (?) talus and the other about 7/8th filled with very thin
(1-2cm thick) slightly wrinkled flows with a void on top, The
skin of the tube is now very visible to both observers, is about
5-10 cm. thick and forms the circumference of the tube. It is
not smooth and circular, but squashed and indented and even folded.
The top of the tube lies just below a single lobate belonging
the rim of the fissure wall.
11:19 2661 080 Stop to sample this surficial lobate flow of zero-age
directly overlying one of the giant tubes. Rock sample 3
is from the intact lobate rook broken from the cross-section exposure.
This lobate is lens-shaped in outcrop and empty. Its skin (roof)
was only about 5cm thick.
11:22 2661 122 Sample in the basket and ready to get underway.
11:23 2660 105 The sediment cover on the lobated seabed is heavy,
about Age 2.0. The floor of the valley here is a mixture
of predominate lobates with subordinate pillows.
11:24 2660 080 We are back on course and proceeding towards the
east wall of the rift. The substrate is mixture of lobates and
pillows with approximately 80 to 90% sediment cover. The pillows
become more rare and lobates become the main lava morphology.
11:25 2660 080 With the sub now driving down a gentle incline
the pillows appear and soon become elongated and trend lengthwise
in the downslope direction eastward. It looks like more sediment
cover on the this pillowed surface (Age 2.5) than the lobates
we had just crossed, but I can not be sure about this. All interstices
are interconnected with sediment, and glassy buds are still omnipresent.
11:26 2662 081 We are driving across an apparently "old (?)"
terrain of pillows and elongated pillows and tubes. No more lobates.
11:27 2665 059 Then we begin our turn to head back across the
rift valley to the west wall. The pillow lava terrain is populated
with a few tall sea pens (?).
11:28 2661 310 Slowing to re-climb the gentle slope that we had
just descended before the turn and see tubes oriented in flow
direction towards us. Pillows and tubes of age 2.5 to 3.0.
100% sediment film everywhere.
11:29 2662 292 Steady on course and now encountering lobates as
the floor flattens out momentarily.
11:30 2662 290 Large collapse pit in the lobate flow ahead. Looking
down into the trap door opened by the roof collapse I can see
the thin (1-2cm thick) sheet-like flows outcrop in the wall of
this hole. They are not bathtub rings, but the lava which has
flowed horizontally through the conduit into which we are looking
and suggest that it is one of the giant tubes (sewer pipes) that
we had observed only in outcrop cross-section. The fallen tabular
roof rock lies scattered on these thin flows and in the distance
I can clearly see frozen tongues of lobate lava pouring back into
the hole from the surface surrounding the hole and dripping down
for 20-40 cm. from the rim. This scene definitely looks like a
view down into one of the giant tubes that had recently seen in
cross-section in the wall of the large fissures on the previous
track across the valley floor. A 5m wide N-S trending fissure
appears just after this collapse pit whose floor is 4m below the
sub.. The terrain then transitions back into pillow lavas from
the lobates and the pillows become the dominate morphology.
11:32 2662 293 Pillow lavas and tubes cut by a narrow fissure
where the floor steps down a meter or so towards the west.
11:33 2655 291 Another fissure cutting the pillow lavas and another
step down to the west. At the next step the floor ahead of the
fault dips gently back towards us and is covered by elongated
pillows and tubes flowing at us (to the east).
11:35 2650 291 We cross a 3m deep fissure perpendicular to our
track whose facing wall has exposed the bedrock of the valley
floor consisting of the cross-sections of pillows and lobates.
Here the pillows lie above the lobates and are topped by the pillows
that make up the surface of the valley floor in our immediate
vicinity.
11:36 2648 289 Pass next over the top of a west-facing escarpment
and look out into water. The altimeter reads 8 meters and then
12 meters as the sub separates from the cliff. Suddenly the bottom
comes into view. It is the 2m wide top of a slab that has detached
from the cliff and is leaning out into the valley ahead of us.
As the sub passes over this slab, the altimeter climbs to 14 meters
. Almost immediately we run into a facing cliff and have to rise
up over it.
11:38 2652 291 Next we cross two more N-S oriented fissures, each
with a small step down to the west and each exposing bedrock outcrop
in its facing wall. Then over a vertical cliff 7 m high with very
little talus at its base. The cliff turns out to be the west facing
wall of a wide fissure as we pass across it and onto a flat floor
of lobate lava. Small collapse pits are present in some of the
lobates. Then on to a thin fissure that cuts N-S through the lobates.
11:40 2656 291. As we continue to motor to the west wall the lobates
pass abruptly to jumbled sheet flows. The apparent sediment cover
on the sheet flows is much reduced, perhaps age 1.5 compared
to age 2.0 as the minimum for the adjacent lobate. The
jumbled sheet flows only last a minute or two of the transect.
11:41 2655 293 As the floor shallows the jumbled sheet flows terminate
as abruptly as they appeared and onlap against older more heavily
sediment pillows. These pillows are cracked and the walls of the
cracks are stained white from presumed hydrothermal exhalations.
We cross over a fissure as the floor valley below steps up one
meter and then another narrow fissure at a second upward step.
The steps are surfaced with pillow lava that has been cut and
offset by the tectonics that opened the fissures and offset the
relief of the valley floor.
11:43 2654 293 Many heavily-sedimented pillows cut by white-stained
cracks. We reach Way Point 4 near the base of the west wall in
a pillowed terrain and turn clockwise to head back across the
valley floor to once again visit its east side. No talus here.
11:44 2657 034 With the turn mostly completed we cross two fissures
separated by a 1 m high horst with the floor everywhere made of
heavily sedimented pillows cut by the tectonics. Most of the pillows
display white coated cracks that dissect the bulbous heads.
11:45 2655 068 The hydrothermal staining is pervasive in cracked
pillows and in the edges of collapse roof rock of the lobate flows
that now begin to surround us.
11:47 2656 067 Soon we reach the belt of jumbled sheet flows recently
passed on the previous transect towards the west wall. Much less
sediment on them than on the flows to each side. The age of these
jumbled sheet flows is age 1.5 compared to the age of
2.0 to 2.5 for the adjacent pillow lava terrain. (Is this
the young lava that John Sinton suspects to have poured south
through the rift valley?).
11:48 2658 067 We transect across the jumbled sheet flows and
back on to older lobates (age of 2.0 ) cut by thin
white-stained cracks.
11:49 2659 068 We now fly over a 3m wide fissure with talus in
its floor . The altimeter shows it to be 3-4 m deep. Terrain cut
by the fissure is both pillow and lobate in morphology.
11:50 2658 067 Head directly into a west- facing wall. It consists
of bedrock outcrop (truncated pillows and lobates) with lobated
lava clearly dripping from the topmost layer of the modern seafloor
down the uppermost face of the wall. The starboard observer concurs.
These lobates are age 2.0.
11:52. 2656 124. With the sub momentarily turned SE we climb this
wall for a height of 4 meters to its top and pass on to large
broken lobates cut by thin fissures.
11:54 2652 064 It is time to climb up in the water to get a transponder
fix.
11:56 2647 068 As we start to descend from this perch above the
bottom, the SIT camera shows the floor below to be pillow lavas
cut by N-S trending fissures . We encounter another west-facing
cliff and ascend it. Pillows outcrop in its wall..
11:58 2649 068 As we crest the cliff lobates are present as the
top most strata superimposed on pillows exposed in the wall. This
seems to be a recurring relationship of lobates as the stratigraphically
highest morphology in the succession of lava flows in the valley
floor locale. The lobates pass along-track into pillows and tubes
as the sub heads down a gentle east-dipping slope. The tubes reach
a 10:1 aspect ratio (l:d) and the lava has clearly flowed eastward
along this seabed.
12:00 2654 069 As we cross a 4 meter deep and wide N-S fissure
we run straight on into its facing wall of outcropping pillow
lavas. We then pass over a fissure on to a heavily sedimented
terrain of elongated pillow and tubes (age 2.5) cut by
thin N-S fissures.
12:03 2652 051 Pillows are the dominate morphology . Reaching
way point 5 near the base of east wall of the rift valley.
12:04 2646 051 As we come upon scattered angular talus (presumably
shed from the east wall that we see dead ahead in the CTFM sonar,
we turn back to the NW to re-cross the valley once again.
12:05 2645 297 Step down a few small 1m-relief and presumably
faulted(?) blocks surfaced with pillow lava with lots of digits
still attached.
12:07 2643 299 Soon we descend a 5-meter high west-facing cliff
with a tall thin Gorgonian coral attached to its crest. Lots of
talus at the base as seen in the down-looking SIT camera.
GAP IN TAPE
12:27 2648 086 The present terrain on the valley floor is now
dominated by lobate lava flows of age 2.0.
12:28 2656 085 On a very smooth floor of little relief we pass
into wavy sheet flows cracked apart and with the walls of the
cracks stained white by hydrothermal fluids. (Is this white a
preserved anhydrite coating?)
12:29 2655 083 Flat and wavy sheet flows with sparse lobates.
Age 1.5 followed by:
12:30 2653 085 Jumbled sheet flows and cracked lobates and a narrow
N-S fissure.
12:31 2654 086 and then more wavy and cracked sheet flows .
12:32 2653 086 Then a large 1-2m wide fissure . The altimeter
reads 5 m as it is crossed and the bottom drops out of visual
sight. The SIT camera reveals talus on the floor of this fissure
that looks much fresher than the surface split by the fissure.
12:33 2653 084 A collapse pit in the lobate lavas. All the broken
edges of the roof rock in its interior are stained white.
12:34 2655 087 Pillows and lobates.
12:35 2655 086 Talus appears at the base of a small west-facing
escarpment. We realize that his is the east wall as we climb up
it.
12:36 2653 082 Still climbing as we observe sections of exposed
bedrock appearing in windows through the talus.
12:37 2644 302 Nine meters higher we turn back to the NW while
still on the wall. Altimeter reaches 14 meters showing the cliff
to be very steep above the valley floor.
12:39 2649 293 As the sub descends the wall the SIT camera show
talus at its base passing outward to hummocky pillows that cast
large shadows.
12:40 2654 282 Back on the bottom of the valley, stopping at Rock
Sample station 4 to sample a pillow bud from this pillowed
terrain of age 2.5.
12:44 2653 300 Underway as pillow lavas pass laterally into what
seems like slightly younger lobates of Age 2.0.
12:46 2651 297 Cross a 5m deep N-S fissure with talus on its floor
and white hydrothermal staining on its walls. Lobated lavas cap
its east rim. They too are cracked and their cracks are also stained
white. These lobates now seem clearly younger than the pillow
lavas near the base of the east wall as judged by less sediment
cover and more glassy surfaces. Soon we ruin into a 5 meter high
east facing wall (presumably of this fissure) with lobates on
its west rim. Signs of layered sheet flow in the face of this
wall beneath the surficial lobate flows. These thinly layered
and horizontally bedded strata which extended with continuity
to out of sight do not look like bath tube rings, but veritable
bedrock outcrop.
12:49 2653 298 Back onto the valley floor comprised of lobate
terrain populated with a few upright pillows.
12:50 2653 298 The lobates now pass into what appears to be relatively
younger (age 1.5) folded sheet flows with some spiral eddies
(whorls) around a pillow sticking up out of the flows like an
island.
12:51 2652 299 Cross a fissure cutting jumbled sheet flows with
white stained walls. Talus abundant. The CTFM sonar indicates
that we are directly approaching the west wall of the valley.
The sub begins to ascend the wall. As it climbs up the talus ramp
into bedded outcrop, the altimeter reaches 11 meters. The wall
is near vertical.
12:53 2640 071 Turn to head back to the east wall. Looking out
into water and beginning the descent. The SIT camera shows a steep
(>45 degree) talus ramp at the base of the west wall.
12:55 070 071 Arriving back on the valley floor. A fissure N-S
cuts the wrinkly sheet flow. Its cracked surfaces as well as the
wall of the fissure are all stained white by presumed hydrothermal
fluids.
12:56 2646 070 Stop and begin to descend onto the substate from
a relatively high altitude for Rock Sample 5 to break off
a piece of folded sheet flow with very glassy surfaces. Age
1.5.
13:06 2653 344 Finishing sampling and getting back underway.
13:07 2652 083 Continue across these regionally-flat wavy sheet
flows with some broken upper surfaces.
13:08 2651 052 The sheet flows rather abruptly pass into what
looks like relatively older (age 2.0) lobate flows of quite
low relief.
13:09 2652 056 A few pillows appear within the lobates.
13:10 2649 054 Cross a wide 2m deep crack or cleft with rubble
at the base of its west side and younger looking sheet flows on
its central floor. They are wavy sheet flows.
13:12 2652 055 Stop for what turns out to be an aborted sampling
effort.
13:15 2652 056 Wavy sheet flows with a few lobates. Then more
wavy sheet flows. Valley floor is very flat here.
13:16 2652 055 Some smooth sheet floor (like a "billiard
table") . Unable to sample find an opportunity to get the
claw into in order to break off a piece.
13:23 2651 003 Aborting this effort and continuing NE to the bounding
wall of the valley. Quickly arrive at the angular talus shed from
this wall.
13:24 2647 054 Climbing the steep wall. Altimeter at 7 meters
as we look from an arms length at the cliff face. Still over a
talus ramp below us.
13:26 2642 314 Reach top of a ledge covered by pillow lavas and
turn to the NW for yet another crossing of the valley.
13:27 2652 315 Look down at wavy sheet flows that have flooded
the valley below us and onlap onto the talus shed from this east
wall.
13:28 2655 316. Stop to sample these sheet flows at the valley
edge as Rock Sample 6. They are both wavy and jumbled with
Age 1.5 and are considerably younger than the nearby pillow
flow above us and at the top of the wall.
13:30 2657 315 Underway over lobate flows.
13:31 2657 314 Cross a couple of small N-S fissures whose walls
are stained white.
13:32 2654 316 Then over a gentle swell of a meter or two where
the flows turn back from sheets to lobates, pillows and elongate
pillows. Then having crossed to the other side of this small elevation
we pass back into smooth sheet flows and the occasional lobate.
13:33 2653 315 Cracked lobates and another narrow N-S fissure
with hydrothermal (?) staining.
13:34 2653 316 A deep fissure with talus at base of its walls
and partly flooded with young jumbled sheet flows (age 1.0).
13:36 2651 314 A 5-6 meter deep fissure floored by what looks
like the same young jumbled sheet flows as in the previous fissure.
13:37 2649 318 Across this second fissure and onto very smooth
sheet flow, and wavy sheet flows with a small collapse indicated
by broken and sagged roof rock.
13:38 2646 315 Arriving once again onto the talus ramp of the
west wall of the valley. This talus is angular with lots of pillow
fragments.
13:39 2641 338 Ascending up the talus ramp and up the sheer face
of the wall. Altimeter reads 9 meters.
13:40 2629 049 At top of the climb we turn back to the NE . The
down-looking SIT camera shows the talus ramp far below with lots
of pillow rubble on it.
13:42 2633 049 Motoring down the west wall.
13:44 2643 063 Lobated lavas on the valley floor from an altitude
of 8 m in the SIT camera and seen overlapping onto the talus,
but some talus has also scattered out on to the top of these lobates.
13:45 2650 063 Back on valley floor. Lobates are quite glassy
here and some wavy sheet flows appear in addition. Terrain is
Age 1.5. Cross a 1m wide and very deep N-S fissure cut
into the wavy sheet flows. Then soon after another fissure <1
m wide but deep. Can't see the bottom of either this one or the
previous one. The altimeter momentarily registers 10m.
13:46 2650 060 Wavy sheet flows of the valley floor with some
lobates on these sheet flows. A clear inter-fingering of contemporary
sheet and lobate flows, some of the sheets wavy, others very smooth.
The smooth "billiard table" ones are cracked and the
polygon-shaped roof rock is slightly tilted into small, sagged
depressions 20-40 cm. deep in their center below the local valley
floor.
13:47 2652 060 Smooth low relief lobates cracked and stained white
on the walls of the cracks.
13:48 2653 063 Wavy sheet flows and even hackly sheet flows, becoming
jumbled sheet flows. Youngest terrain observed so far. Maybe
Age 1.0. Crossing a 3m deep N-S trending fissure in the valley
floor\ cut into the wavy sheet flows. Hydrothermal (?) staining
on its uppermost walls.
13:49 2652 062 Valley floor remains quite flat and is covered
by wavy and smooth sheet flows.
13:50 2653 059 Striated sheet flow and some very low-relief smooth
lobate flows. Then more wavy sheet flow. All of the same age and
grading one into the other. Hydrothermal white staining everywhere
in thin cracks with spaghetti worms blown around by Alvin's thrusters
followed almost immediately by talus from the approaching east
wall.
13:51 2653 061 Arriving at the east wall and climbing the narrow
talus ramp to then vertically ascend the cliff face.
13:53 2637 064 Altimeter registers 13 meters as we look directly
at the face of this wall high above the top of the talus ramp.
Pillows visible in the outcrop.
13:54 2646 071 Climbing up a massive unit of the bedrock exposure
covered in streaks by fine pebble to sand size talus and some
large blocks precariously perched on narrow ledges. More talus
on these narrow ledges and then climbing up along additional outcrop.
The valley wall is itself fissured into vertical cracks and looks
like it could peel off with the slightest nudge.
13:56 2635 071 Still climbing while looking directly at the sheer
wall. Lots of tiny fissures in the wall (vertical joints) and
outcrop exposure of truncated pillow lavas.
13:58 2624 013 . As we approach the top we see tongues of frozen
lava that had partly dripped down into the void from the rim.
We momentarily stop for more observations and then continue turning
back to the NW to Way Point 16. The pillow lavas at the top of
zero age are in the highest stratigraphic position and make up
the modern rim floor with Age 2.5.
14:00 2626 345 Motoring out into the water column to begin long
descent to the valley floor at the bottom of the cliff.
14:02 2634 312 The down-looking SIT camera shows talus below us
on ledges and the talus containing many round pillow fragments.
The ledge surfaces are the same pillow lava terrain just seen
at the top,
14:04 2645 316 The altimeter registers 14 meters with rubble and
talus barely made out by the SIT camera. As we continue powering
down, it looks like the sheet flows of the valley floor overlap
and cover the base of the talus ramp, though some large blocks
have tumbled out onto the sheet lava surface.
14:06 2654 315 Back on the wavy sheet flows of the valley flow
and stopping for Rock Sample 7. Hydrothermal stains are
pervasive on all broken surfaces. The stain here is both white
and rust colored. Lots of unknown floating creatures and shrimp
in the water around us. Sampling the glassy wavy sheet flow.
14:11 2655 342 Underway from this sampling station and flying
through a sea of floating spaghetti worms set free by the turbulence
of the sub's thrusters or bow wave. The lava surface looks very
young (Age 1.0). Lots of hydrothermal staining in thin
cracks. As we head NW there is a huge tabular surface out the
port-side viewport. It is a large sliver of the east wall that
has fallen out onto the valley floor. Its top surface (former
seafloor) dips 45 degrees down to the west. It takes on the appearance
of an inward tilted block and the joint surface exposed on its
eastward-dipping back (detached surface) is extraordinarily smooth.
14:14 2652 316 We next cross a very flat valley floor lava flow
composed of smooth sheet flows cracked by thin millimeter wide
fissures.
SMALL GAP IN TAPE
14:21 2656 314 The CTFM sonar shows us rapidly approaching
the west wall having crossed the valley floor. Angular and tabular
talus and broken pillow fragments with no sediment cover (a very
fresh rock fall) are soon pervasive.
14:22 2647 314 Climbing the west wall talus slope and turning
back to the NE and stopping to sort out a problem with a VCR.
14:31 2655 048 Problem solved, the VCR back on. We are now out
on lobated lavas of the westernmost side of the valley floor.
14:32 2655 049 Moving across low relief smooth lobates lightly
dusted with sediment (age 1.5).
14:33 2653 049 Cracked and stained wavy sheet flows and striated
sheet flows.
14:34 2653 048 Passing into wavy sheet flows and a few lobate
flows of perhaps the same eruption or near contemporaneous eruption.
If anything, the lobates have the appearance of over-spilling
onto the sheet flows rather than visa-versa. Cross a 3 meter deep
fissure cut through the lobate flows. Some small steps (<1m)
down of the seafloor as we proceed to the NE.
14:35 2652 048 We soon encounter wavy sheet flows and lobates,
this time quite clearly flowing out on top of the sheet flows.
Very little sediment dusting on these youngest flows.
14:36 2651 050 A fissure cuts a very flat sheet flow surface,
then some blocky talus immediately followed by a 3m wide deep
fissure. The altitude registers 6 m as we cross over this crack.
Flat sheet flows pond in its floor and these sheet lavas are only
very lightly dusted with sediment (Age 1.0). Hydrothermal
white staining is everywhere in thin cracks in the lava.
14:38 2650 049 Further out beyond this fissure the locally flat
and featureless valley floor is now a wavy sheet flow.
14:39 2653 048 Stop for Rock Sample 8 on this relatively
young wavy sheet flow.
14:43 2652 048 Back underway to the NE to continue to cross the
valley floor to its east side. Wavy sheet flows continue among
rare lobates. The few lobates appear to have flowed out onto the
sheet flows as judging from their contacts. Smooth sheet flow
and some lobates transitional into a wavy sheet flow morphology.
14:45 2653 049 Angular talus and broken pillow lavas and massive
blocks of basalt.
14:46 2652 049 Crossing a broken lava surface as if squeezed up
in a thrust. Talus contains detached pillow heads. Lots of loosely
scattered rubble among the shattered pillow heads and pillow trunks.
14:47 2651 046 More talus and allochthonous pillow heads. The
view out the porthole presents a deep wide cleft below us. As
we cross it the altimeter registers 19 meters. Approaching its
east wall, one can see frozen lobate flows dripping down into
the cleft from the flooded valley floor. The starboard observers
concurs. The west-facing wall presents a cross-section of the
valley floor in which we see layered outcrop. Passing over the
top of this wall we look down to see it as both vertical in relief
and sheer in smoothness. The outcrop is thinly (20-30 cm.) and
massively (several meters) bedded strata with no sign of the round
cross-sections of pillows..
14:49 2634 049 Coming up a ramp of small fist-sized and black
glassy sand onto widespread angular talus.
14:50 2622 054 We are now high above the bottom as we climb the
steep east wall. It consists of layered pillow and lobate flows
viewed in outcrop .
14:52 2611 132 As we reach the top of this east wall and stop
on its capping pillow lavas, we find this high surface to be heavily
covered in sediment and age 2.5. Rock Sample 9 is
from this cap rock.
14:54 2610 127 It is time to leave our perch on the cliff. Altimeter
registers 15 meters to the top of the talus ramp directly below
us. The cliff face is near vertical >80 degrees).
14:56 2604 325 We now motor out into the water column to begin
a power descent to the valley floor below. At 2614 m depth along
the cliff face, the altitude is 19m. At 2620 m the altitude is
31m. We can see the wall fall off below us in the down-looking
SIT camera. Talus lies far below.
14:59 2647 325 The bottom comes into view out the porthole as
we land on the valley floor. Very glassy lobate flows of Age
1.5. The sediment film is rust colored. Only 30% sediment
cover.
15:00 2654 323 Wavy sheet flows with occasional smooth lobate
flows. N-S fissure cuts through these lobates.
15:02 2658 323 Folded and pleated sheet flows now pass into wavy
and jumbled sheet flows all of Age 1.5 to possibly 1.0.
15:03 2656 321 We re-cross the large N-S axial cleft that has
cut deeply through mostly lobate flows. These lobates seem to
have flowed out onto the adjacent sheet flows. The altimeter registers
6 meters as we cross this large fissure. The flow morphology on
the west side of this fissure is now dominantly lobate flows.
15:04 2654 322 Cracks in lobate flows are stained white on their
broken faces. Lobates continue to dominate the local landscape.
15:06 2658 322 A fissure cuts across the lobates and through a
rare pillow mound. A collapse pit lies directly in front of us
in the lobates with pieces of the broken roof rock scattered on
its floor.
15:07 2660 325 Another N-S trending fissure cutting through the
lobate lava surface.
15:08 2659 323 It is time to stop for Rock Sample 10 located
in a small pocket of wavy sheet flow amongst the lobates. This
glassy flow looks quite fresh with an age of 1.0.
15:11 2659 092 Completing the sampling and starting to turn and
move NW towards the west wall to finish this last crossing of
the valley floor.
15:12 2649 286 Encounter talus shed from the west wall. It looks
exceedingly fresh and may represent a recent rock fall. In this
case the talus is all strewn out onto the lobate and wavy sheet
flows that otherwise abut against the valley wall. Beginning to
climb the talus ramp and the east-facing sheer wall.
15:13 2647 286 As we view the wall straight ahead of us, the altimeter
registers 14 meters. We see a large sliver of this wall beginning
to peal away as we peer into an open joint behind it, This sliver
is actually leaning out in the direction of the valley floor.
We climb up along the widening gap between it and the main wall
only to discover that what we think is the main wall is another
1-2 meter wide (direction into the wall) and ten meter high sliver
of the bedrock, very precariously standing nearly upright but
clearly pealing away to the east from a vertical joint surface.
Talus is present in the open joint that broaden upwards. The summit
of each observed sliver is capped by heavily sedimented pillow
lava of Age 2.5.
15:16 2621 285 More sheer bedrock of layered pillow lavas and
truncated tubes in the exposed face of the west wall as we continue
to climb. Occasionally there is scree running down narrow chutes
that are shallow indentations (probably opening joints)in the
wall. Glassy sand and small pea-sized gravel populate many of
these chutes and accumulate in cones on ledges in a feature that
looks like miniature alluvial fans except the slope is steeper.
Then to our amazement the wall that we have been climbing is yet
another 2-3 meter thick sliver (the third 0ne) partly peeled away
from the vertical valley-wall along the valley-parallel joint
surface. The on these near-vertical faces outcrop is now near
100 percent bedrock. comprised of layered pillows whose round
and radially cracked cross-sections make the whole face look like
a poka-dot covered cloth.
15:18 2608 286 Still climbing the near vertical face Scree become
100% and then disappears to expose more bedrock.
15:20 2597 283 The wall is now total outcrop
15:21 2591 349 At some 70 meters above the valley floor below
we reach what we believe from our dive map to be the summit of
the west wall. It is coated with old pillow lava heavily sedimented
of age 2.5 to age 3.0. We stop to take a last sample, but
the effort to position the sub is great and time runs out. While
hanging here at the top of the cliff, the altimeter reads in excess
of 20 m down into the opened joint below us.
15:00 2590 358 After much frustration and no success in sampling,
the dive ends by releasing the ascent weights. Thank you Dudley
Foster for a insightful and thrilling trip.
.