Mission
Dive and Discover’s Expedition 5 will explore the undersea
volcanic slopes of the remote Galápagos islands of Fernandina
and Isabela. Though best known for his theory of evolution based
on biological observations made in the Galápagos, Charles
Darwin was first captivated by the geology of the islands when
he traveled there more than 160 years ago. The natural wonders
of Galápagos volcanoes and animals led him to develop several
scientific theories which revolutionized biological and geological
sciences in the 19th century.
Now, scientists on Expedition 5 will use high-tech oceanographic
instruments to make new geological discoveries in the Galápagos.
They will map and sample the submarine sides of two volcanoes that
rise more than 4,500 meters (14,760 feet) above the seafloor. The
detailed maps will give scientists clues to understand the geologic
history of these volcanoes. The chemistry of the lava will tell
them about the Earth’s interior and how molten rock or magma
is formed in the mantle and how it erupts under the ocean.
Join scientists, students, technicians and the ship’s crew
on board the research vessel RV Roger Revelle of the Scripps Institution
of Oceanography as they explore the underwater slopes of volcanoes
in the Galápagos Islands. The month-long expedition starts
on August 24, 2001, when the ship sails from Puerto Caldera, Costa
Rica. After a brief stop in the Galápagos Islands to take
on personnel and explore the island, we head out to sea for 3 weeks
to conduct our expedition. Join us!
Objectives
In 1835 a young British naturalist named
Charles Darwin visited the Galápagos Islands during the legendary voyage
of HMS Beagle. Darwin’s keen observations of the islands’ singular
animal life inspired his revolutionary theories of biological
evolution. But that’s just a part of the story.
Created by volcanic eruptions over the past
3 million years, the Galápagos Islands rise to elevations of more than
1600 meters (5300 feet) above sea level. But these are just the
more visible tips of much larger volcanic platforms that extend
another 3000 meters (9800 feet) down to the seafloor! Now, scientists
from several US research institutions and universities will explore
the portions of these extraordinary islands that have been hidden
by the ocean. Their mission constitutes the most comprehensive
mapping, sampling, and deep-sea photography of the seafloor around
the western Galápagos Islands ever done.
The Galápagos Archipelago stretches over 400 miles (>640
kilometers) in the eastern Pacific Ocean near the Equator. It
includes thirteen major islands, six smaller islands, and dozens
of islets. Discovered in 1535 by the Bishop of Panama, Thomás
de Berlanga, the islands served over succeeding centuries as
a re-provisioning stop for pirates and whalers, who regrettably
plundered the islands’ giant tortoises and introduced animals
and plants that profoundly changed the islands’ ecology.
Most of the major islands of the Galápagos,
including those we will study, have had recent eruptions. The
Galápagos
lie atop a hotspot -- a dot on Earth’s face where a
narrow plume of hot mantle rocks rise from deep within the planet
and burst through Earth’s crust to create seafloor volcanoes.
In a way, hotspots like the Galápagos give us a rare window
to peer into processes that we can’t easily see because
they occur deep within the Earth.
Among the questions we are exploring are
these: Where does the magma, or molten rock, come from to feed
volcanic eruptions on the Galápagos? Can we find telltale chemical clues in
magma that can teach us about the formation of Earth’s
mantle and the early history of the Earth? How do seafloor lava
flows eventually build islands? How does the Galápagos’ underwater
volcanic terrain compare with that of hotspot islands, such as
Hawaii and Iceland, and with that created by volcanoes at mid-ocean
ridges?
To help answer these questions, we will study
the submarine flanks of the two westernmost Galápagos Islands: Isabela
and Fernandina. We will use a multibeam sonar system mounted
on the hull of Scripps Institution of Oceanography’s RV
Roger Revelle to collect data to make bathymetric maps of seafloor
topography. In addition, the University of Hawaii’s MR-1
side-scan sonar system, which is towed behind the research ship,
will collect data to create images of submarine lava flows that
look almost like photographs taken from an airplane. They will
show the locations of different lava flows and volcanic vents
and the pathways in which lava has traveled down the undersea
slopes.
Once we have mapped the seafloor around Isabela
and Fernandina, we will use Woods Hole Oceanographic Institution’s
one-of-a-kind digital deep-sea camera system to photograph
seafloor lava flows. Using the sonar maps and photographs as
guides, we will sample the seafloor lava with a dredge and
rock corer. The rocks initially will be described, cut, and
sampled on board. Their chemistry will be analyzed after the
cruise in several US research laboratories.
Each day the scientific and technical teams
on the ship will collect new images and samples of the undersea
volcanic terrain around these islands that have never been
seen before. Join us as we piece together the magmatic and
volcanic history of Galápagos
undersea volcanoes.
[Back
to top]
|
Email
to friend
