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20 August, 2001

August 20, 2001

Popping Rocks and Lava Tubes???

This morning the science lab was abuzz with excited scientists. Two dredges came up in the early hours this morning that were very interesting, to say the least.

Keeping in mind the Gakkel Ridge is the slowest spreading and least volcanically active ridge on the planet, finding fresh volcanic rock could be difficult. However, the rocks that came up in recent dredges show evidence that it may be otherwise. In dredge #26, "popping rocks" came up. These are rocks that form by the quick cooling of magma. Magma has gas under high pressure that is trapped when it solidifies. When these rocks are then brought from the ocean floor to the surface, the pressure on them is decreased and the gas wants to escape. This can cause the rocks to make popping noises and actually move and break! Several scientists observed this unique action early this morning.

On dredge #27, another batch of fresh volcanic rocks were brought to the surface. These rocks, called "lava tubes", formed when lava erupted onto the ocean floor and cooled when it hit the water. The cooling occurred such that the rocks grew slowly upward in a pillar-like manner. The lava tubes recovered today were smooth, shiny, and covered with large crystals. They ranged in size from a few inches to a few feet. To bring a 2-foot long lava tube up in a dredge without it breaking apart was quite miraculous!

Part of the excitement of being here for me is discovering the undiscovered. We seem to have found so many amazing things in our 3 weeks at sea, and our mission is only 1/3 complete. Who knows what other amazing discoveries await us!

<> Dr. Dave Graham holds a lava tube recovered from a dredge that he supervised.

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