Humps Of Particles In The Gulf Stream

Peculiar humps or hills of particulate material, thousands of feet long and hundreds high, have been observed in the Florida Current with ultrasensitive, 20-kilohertz sonar. The humps extend from the bottom of the oceanic mixed layer to near the surface. Sediment and plankton probably make up the humps, but the actual constitution and cause of the concentrations are unknown. Conceivably, currents could concentrate the particulate matter; so could some sort of coordinated, collective biological activity.

(Proni, John R., et al; "Vertical Particulate Spires or Walls within the Florida Current and near the Antilles Current," Nature, 276:360, 1978.)