Dipping layered consolidated sedimentary block partially buried in soft sediment on the upper slope surveyed during this dive. These blocks, most buried by soft sediment, formed a hummocky seafloor topography that suggests: 1) that these sub-seafloor sediments have been pushed upwards by rising deeper salt/evaporites and/or 2) that gravity has caused slumps/submarine landslides on this ~7-8 degree slope.

Dipping layered consolidated sedimentary block partially buried in soft sediment on the upper slope surveyed during this dive. These blocks, most buried by soft sediment, formed a hummocky seafloor topography that suggests: 1) that these sub-seafloor sediments have been pushed upwards by rising deeper salt/evaporites and/or 2) that gravity has caused slumps/submarine landslides on this ~7-8 degree slope. Image courtesy of NOAA Okeanos Explorer Program, Gulf of Mexico 2014 Expedition. Download larger version (jpg, 1.4 MB).

Dive 06: Keathley Canyon
April 18, 2014
26.442567872; -93.46659858, 2,160 meters
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Okeanos Explorer EX1402L3

Dive 06: Keathley Canyon. Video courtesy of NOAA Office of Ocean Exploration and Research. Download (mp4, 34.5 MB)

Dive 06 was our second dive in Keathley Canyon, approximately 20 kilometers south of Dive 04, and began at a depth of 2,130 meters. The initial view of the seafloor showed unconsolidated sediment, with pronounced ripples. During our first transit, Deep Discoverer (D2) captured some fantastic imagery of several sea cucumbers swimming and eating, as well as a deep-sea lizardfish and a number of shrimp. Heading to Waypoint 2, we saw a number of cerianthid anemones and a thread leg shrimp. A few swimming polychaetes, liparid fish, and cutthroat eels were sighted and tripod fish were common. Sediment cover featured mostly pteropod shells with little to no ripples; on hard bottom, there were a few small white sponges and fly-trap anemones. Throughout the transit, we also saw several single stalked bamboo corals, the only species of coral on this dive. As the dive progressed, there was an increase in hummocky seafloor with associated hard ground and layered outcrops of more consolidated material. Individual hummocks were often a meter or more in height. Burrows in these outcrops were common. Biota in this area included sea cucumbers, cutthroat eels, rattail fish, shrimp, and several glass wedding sponges. Towards the end of the dive, D2 came across a set of Paleodictyon holes, one of the highlights of the day. Virtually identical, enigmatic “trace” marks have been seen in the geologic record for some 600 million years, and their cause is still being debated.