Features and Deposits Features and Deposits Tumuli and sheet flows have recently been found in submarine lava flow fields. Tumuli form as the interior of the flow inflates. The presence of tumuli and long sinuous ridges on submarine lava flow fields suggests that lava tubes help distribute the lava.
Tubes help lava travel tens of kilometers from their vents.
This photo shows young sheet flow lava on the Cleft segment of Juan de Fuca Ridge. Looking down into eruptive fissure, southern Juan de Fuca Ridge. Note pillow lava frozen as it flowed back into fissure. Eruption probably took place in early-mid 1980s. NOAA towed camera system.