 |
|
|
|
|
|
|
|||||
|
|
|
|
|||
|
|||||
Hawaii Cruise Logbook |
April 12, 2001: Leg 2; Day 12 |
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Dive 291 was conducted 1 km off
shore of Kealakekua Bay, tormentingly close to land for those who have
been at sea for two week. From the deck the monument that marks the spot
where Captain Cook died and houses on the shore were clearly visible. The
scent of land was in the air. One objective was to collect samples of the
waters using a device that strips radium from seawater to determine if the
waters of the Bay have been diluted by submarine springs. This bay is one
of the few places on the southern side of Hawaii that is wet enough to
support off shore springs. A 3 km long transect along the top of a
150-meter deep fossil reef platform which wraps around the shore was
conducted. We also collect coral samples from the tops of the platform,
which will be dated. Four lava flows were seen that crossed over the top
of the reef and occasional pillows dribbled over the edge of the reef
front.
|
||||
|
||||
 Good
sea conditions on the leeward side of the Big Island, allowed us to
continue our tour of the northern edge of the South Kona landslide today.
We dove between the pillow basalts and broken volcaniclastic rocks we
found on our previous dives, to look for the boundary between them. We
traversed a north facing marginal scarp on the slide, crossing from broken
rock on the seaward edge, onto large flow fronts containing bulbous
submarine pillow lavas. The lavas were surrounded by a sea of glassy
basalt gravels, probably derived from recent lava flows from Mauna Loa.
The package we traversed appears to define a complete stratigraphy of the
southeast flank of Mauna Loa, from which we hope to unravel the dramatic
growth and collapse history of the giant volcano.
|
||||
|
