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 Daily Updates: August 2001
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guaymas basin map
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.

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RV Knorr
ROV Jason

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!

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.

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