Photo Essay: Fire and Ice off Cascadia
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Ice ages come and go. So do pulses of volcanic eruptions on land and at sea, maybe, on roughly the same time scale. Could the two be related? A recent two-week oceanographic expedition aimed to find out. The overarching hypothesis: As water accumulates on land in the form of massive ice sheets, the pressure of the overlying ice puts a lid on volcanoes. A corresponding drop in sea level allows volcanic vents on the seafloor to let loose. Then, when the planet warms, causing ice to melt and sea levels to rise, hydrothermal venting is suppressed, while volcanoes on land become more active. These interconnected processes, which release carbon dioxide during eruptions on both land and sea, may help regulate global climate in a seesaw fashion. To investigate this idea, a team of scientists from Lamont-Doherty Earth Observatory and Harvard University sailed last fall off the Pacific Northwest aboard the R/V Atlantis. They drilled into sediments holding geochemical tracers of past hydrothermal eruptions to see if they have varied on ice-age like cycles . They also sampled sub-surface lava deposits, and mapped the underlying seafloor. On land, in a project led by Harvard, old lavas in the Cascades Range of Washington, Oregon and California were sampled and dated. Part of the Volcanoes, Ocean Ice and Carbon Experiments (VOICE) project, the investigation is a collaboration between Lamont-Doherty, Harvard, Penn State, the U.S. Geological Survey and Oxford University. Gisela Winckler, a Lamont-Doherty geochemist on board, organized photos taken during the cruise into the above slideshow.
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