"Pop Rocks" from the Ocean Floor

In 1960, unusual deep-sea volcanic rocks were dredged up from the waters off Mexico, near Guadalupe. They broke apart with loud popping noises when brought to the surface. A very few additional sources of popping rocks have been found, mainly on the Mid-Atlantic Ridge, but it took 45 years to relocate the site of the original discovery. Scripps oceanographers have finally accomplished that, finding the rocks on a volcano 3,200 meters down. The rocks "pop" due to concentrated bubbles of volcanic gases trapped inside. When the rocks escape the confining pressure of the deep sea, the bubbles expand with enough force to break the rocks open. The gases in the bubbles will give geologists a window back in time to examine the concentrations of these elements and compounds (helium, argon, carbon dioxide, water vapor, etc.) trapped when the mantle was being formed.