Visual observations of the sea floor subduction line in the middle-america trench.

Four dives were made to the floor of the Middle-America Trench with the U.S. Navy's deep research submersible DSV Turtle.

Cretaceous drowning of reefs on mid-pacific and Japanese guyots.

Reefs dredged on guyots of the Mid-Pacific Mountains and the Japanese Seamounts yield middle Cretaceous fossils, indicating that submergence killed off the fauna of the reefs sometime during the Albian-Cenomanian. Eustatic rise of sea level is probably responsible.

Jurassic sandstone from the tropical atlantic.

The oldest sediment yet sampled from the abyssal margins of South America, late Jurassic (or possibly very early Cretaceous) shallow-water, coarse-grained, calcareous sandstone containing palynomorphs and mollusk prisms, was recovered from a depth of 4400 meters on the seaward scarp of the Demerara Plateau. The sandstone was deposited in a shallow, late Jurassic epicontinental sea after the initial stages of rifting when the newly created Atlantic began to founder.

Geological history of the Western north pacific.

A considerable portion of the abyssal floor of the western North Pacific was already receiving pelagic sediment in late Jurassic time. Carbonate sediments were later replaced by abyssal clays as the basin deepened and bottom waters became more aggressive. The resulting facies boundary, which can be recognized on seismic profiles, is broadly transgressive; it ranges in age from mid-Cretaceous in the western Pacific to Oligocene in the central Pacific.

Knoll and Sediment Drift near Hudson Canyon.

A parallel-bedded accumulation of sediments forms a low ridge on the upcurrent side of a partially moated knoll. These sediments were deposited beneath a southwestward-flowing current where it is locally decelerated by the obstructing knoll.

Opal phytoliths in a north atlantic dust fall.

Minute bodies (less than 80 microns) of isotropic silica, originally precipitated by terrestrial plants, are found together with freshwater diatoms in falls of dust over the ocean. Eolian transport from Africa can explain the occurrence of similar plant remains in deep-sea sediments of the equatorial Atlantic as far west as the Mid-Atlantic Ridge.

Shaping of the continental rise by deep geostrophic contour currents.

Geostrophic contour-following bottom currents involved in the deep thermohaline circulation of the world ocean appear to be the principal agents which control the shape of the continental rise and other sediment bodies.

A Wandering Enteropneust from the Abyssal Pacific, and the Distribution of "Spiral" Tracks on the Sea Floor.

Certain coiled tracks appear in photographs from the bottom of most oceans and are abundant in some regions. Enteropneusts are among the forms responsible for such tracks although, despite earlier evidence, they are rarely considered to be either active or abyssal.

Sands of the Mid-Atlantic Ridge.

Sands collected at 24 locations along the crest of the Mid-Atlantic Ridge between 57 degrees S and 38 degrees N consist predominantly of olivine, diopsidic augite, hypersthene, enstatite, amphibole, quartz, plagioclase, and volcanic glass, suggesting an olivine tholeiitic source. Eight cores contain relatively pure mineral sands; three of these cores reflect local volcanic activity. In 16 cores the manganese-coated mineral grains are mixed in a current-winnowed foraminiferal sand or ooze.

Modern Graywacke-Type Sands.

A preliminary study of more than 100 deep-sea cores from abyssal plains has revealed two examples of recent muddy sands of the graywacke type which, together with the microcrystalline matrix, form a bimodal-size distribution sands have a well-sorted framework of quartz, feldspar, and rock fragments which, together with the microcrystalline matrix, form a bimodal-size distribution that is also typical of ancient graywackes. The matrix is considered to be primary.

Continuity of Mid-Oceanic Ridge and Rift Valley in the Southwestern Indian Ocean Confirmed.

The existence of a continuous, rifted, mid-oceanic ridge in the southwestern Indian Ocean, previously predicted by us, has been confirmed by soundings taken by the research vessel Vema during the expedition now in progress.