Geologist Eric Fernandez examines an outcrop of pyroclastic rocks along the banks of the Río Genio, on the northern side of Cocos Island. Pyroclastic rocks were erupted either immediately prior to or contemporaneously with trachytic rocks forming a lava dome. Pyroclastic rocks are thickest on the northern side of the island, which may represent the topographic high of the old seamount.

Photo by Pat Castillo, 1984 (Scripps Institution of Oceanography, University of California San Diego).

This image is made available under the Creative Commons BY-NC-ND 4.0 license terms.

Isla del Coco