Sea Floor Basalt
In Our Region:
This particular sea floor basalt in Fossil Mysteries was collected by Scripps Institution of Oceanography’s researchers. Sailing aboard the R/V Revelle, scientists on the Alarcon Expedition dredged this basalt from the sea floor, thousands of feet below the oceanís surface.
When analyzed chemically, scientists learned that the rock closely matches rocks from mid ocean ridges under the Pacific Ocean. That was a surprise, since they expected this basalt to have traces of rock melt from the edge of the North American continent, as did basalts from further north in the gulf.
Studies like these add to our understanding of how landscapes in southern and Baja California have evolved over time. Because this very young rock looks like other Pacific Ocean sea floor rocks, we have learned that when the North American continent moved west over the mantle beneath the Pacific Ocean, rifting opened a “window” that allowed melted Pacific magma melt to rise and erupt into the waters of the gulf.
Photograph: François Gohier