This activity may be either mediated by groundwater flow from El Hierro or by recent eruptions of Henry Seamount.
The seamount features ridges and gullies and a sharp slope break with respect to the surrounding ocean floor.
The seafloor on the seamount itself is covered by sediments[2] and pelagic ooze containing foraminifera and calcareous nannofossils has been found on the summit.
[3] Underwater cameras have observed deposits of lapilli and volcanic ash,[4] outcrops of basement on Henry Seamount and pale sediment, while clam shells are widespread in the summit region.
The rocks show evidence of alteration by seawater and metasomatism; the baryte appears to have been emplaced hydrothermally.
[2] Its formation appears to be unrelated to both the Mid-Atlantic Ridge and the Canary hotspot; it may instead be related to mantle phenomena at the edge of the Northwest Africa craton[11] and with structures of the ocean floor.