New MBARI research on a field of pockmarks—large, circular depressions on the seafloor—offshore of Central California has revealed that powerful sediment flows, not methane gas eruptions, maintain these prehistoric formations. New MBARI research on a field of pockmarks—large, circular depressions on the seafloor—offshore of Central California has revealed that powerful sediment flows, not methane gas eruptions, maintain these prehistoric formations. Earth Sciences Environment Phys.org – latest science and technology news stories