99
dust
frame dredge covers more ground than the pipe dredge, but is far more likely
to get caught under ledges that cannot be fractured. ~bottom samplers.
drift the transport of organisms or objects by water currents. When for organisms this transport is independent of the (swimming) activity, as in the case
of drift of eggs and larvae, the term passive drift is used. ~sediment drift.
drift current current that is directly driven by wind stress. The classical theoretical
solution for the structure of a drift current is given by the Ekman spiral solution.
Empirical relations between wind and current that have been established for
different regions are often strongly influenced by local conditions and by the
quality of the current and wind data used. They usually result in a wind factor
that gives a (mostly linear) relation between wind and drift current.
drift nets ~nets.
drilling making a circular hole in rock or sediments with a drill or other cutting
tool. In the ordinary rotary drilling method the material from the bore hole is
crushed, and some characteristics of the undisturbed rock section penetrated can be obtained afterwards by well logging. If one wants to preserve a core
from the bore hole, a core drill is used. ~bottom samplers.
DSDP ~Deep-Sea Drilling Project.
DSL deep scattering layer, ~scattering layer.
DSP ~diarrhetic shellfish poisoning.
dumping ~ocean dumping.
Dunbar line dividing line in the North Atlantic Ocean between the cool-temperate and subarctic zones; a zoogeographical term often used in taxonomic literature.
dune (1) (subaerial) low mound, ridge, bank or hill of loose wind-blown granular material (sand, volcanic ash, often mixed with shell fragments), either
bare or covered with vegetation; retains a characteristic shape even when
moving over considerable distances. ~coast; (2) (subaquatic) large sand ripple, ~megaripple.
dust (geol.) dry, solid matter consisting of clay- and silt-size particles, so finely divided that they can be easily picked up and carried over long distances
in suspension in the atmosphere. Sources of marine dust include, e.g.,
deserts, volcanic eruptions, salt spray from the seas, and extraterrestrial
dust
frame dredge covers more ground than the pipe dredge, but is far more likely
to get caught under ledges that cannot be fractured. ~bottom samplers.
drift the transport of organisms or objects by water currents. When for organisms this transport is independent of the (swimming) activity, as in the case
of drift of eggs and larvae, the term passive drift is used. ~sediment drift.
drift current current that is directly driven by wind stress. The classical theoretical
solution for the structure of a drift current is given by the Ekman spiral solution.
Empirical relations between wind and current that have been established for
different regions are often strongly influenced by local conditions and by the
quality of the current and wind data used. They usually result in a wind factor
that gives a (mostly linear) relation between wind and drift current.
drift nets ~nets.
drilling making a circular hole in rock or sediments with a drill or other cutting
tool. In the ordinary rotary drilling method the material from the bore hole is
crushed, and some characteristics of the undisturbed rock section penetrated can be obtained afterwards by well logging. If one wants to preserve a core
from the bore hole, a core drill is used. ~bottom samplers.
DSDP ~Deep-Sea Drilling Project.
DSL deep scattering layer, ~scattering layer.
DSP ~diarrhetic shellfish poisoning.
dumping ~ocean dumping.
Dunbar line dividing line in the North Atlantic Ocean between the cool-temperate and subarctic zones; a zoogeographical term often used in taxonomic literature.
dune (1) (subaerial) low mound, ridge, bank or hill of loose wind-blown granular material (sand, volcanic ash, often mixed with shell fragments), either
bare or covered with vegetation; retains a characteristic shape even when
moving over considerable distances. ~coast; (2) (subaquatic) large sand ripple, ~megaripple.
dust (geol.) dry, solid matter consisting of clay- and silt-size particles, so finely divided that they can be easily picked up and carried over long distances
in suspension in the atmosphere. Sources of marine dust include, e.g.,
deserts, volcanic eruptions, salt spray from the seas, and extraterrestrial