183
magnetic anomaly
M
MAC ~maximum allowable concentration.
macrobenthos bottom-living organisms larger than 1 mm, ~benthos.
macronutrients those nutrients that constitute the main part of nutrition, such
as organic molecules, phosphate (~phosphorous cycle), nitrate and ammonia.
macrophytes the larger, macroscopic, multicellular algae as opposed to singlecelled, microscopic microphytes.
macroplankton large-sized (between 2 and 20 mm) planktonic organisms, ~plankton.
Madreporaria (syn. Scleractinia) true or stony corals, order of the class Anthozoa
(phylum Cnidaria). These corals are solitary or colonial, and have a heavy, external calcareous skeleton. They have relatively small polyps. Reef-forming colonies,
coral reefs, are restricted to clear water in shallow tropical seas, but solitary
corals can even be found in the deep sea.
madreporite ~Echinodermata.
magma a hot silicate melt within the earth containing suspended crystals and
dissolved gases. Rocks originating from the crystallization and solidification
of magma are said to be magmatic. ~Iava.
magnetic (earth) field the earth's magnetic field is thought to derive from flow patterns in the liquid outer core (~earth's internal structure). Its mean field intensity
at the surface is ca. 0.5 Gauss (equivalent to 50 10- 6 Tesla). At any point on the
earth, the total field intensity can be resolved in the intensity of the horizontal component and the intensity of the vertical component. The direction is
described by the deviation from the north (declination) and the angle with the
horizontal (inclination). The earth's magnetic field resembles for 90 % a
dipole field with its axis declined 11 0 from the axis of rotation. The small additional nondipole field is responsible for irregularities of the field in distribution and time (secular variation). ~magnetic anomaly and ~magnetic polarity.
magnetic anomaly any departure from the theoretical magnetic (earth) field. The
earth's magnetic field can be locally affected by induced or remanent mag-
magnetic anomaly
M
MAC ~maximum allowable concentration.
macrobenthos bottom-living organisms larger than 1 mm, ~benthos.
macronutrients those nutrients that constitute the main part of nutrition, such
as organic molecules, phosphate (~phosphorous cycle), nitrate and ammonia.
macrophytes the larger, macroscopic, multicellular algae as opposed to singlecelled, microscopic microphytes.
macroplankton large-sized (between 2 and 20 mm) planktonic organisms, ~plankton.
Madreporaria (syn. Scleractinia) true or stony corals, order of the class Anthozoa
(phylum Cnidaria). These corals are solitary or colonial, and have a heavy, external calcareous skeleton. They have relatively small polyps. Reef-forming colonies,
coral reefs, are restricted to clear water in shallow tropical seas, but solitary
corals can even be found in the deep sea.
madreporite ~Echinodermata.
magma a hot silicate melt within the earth containing suspended crystals and
dissolved gases. Rocks originating from the crystallization and solidification
of magma are said to be magmatic. ~Iava.
magnetic (earth) field the earth's magnetic field is thought to derive from flow patterns in the liquid outer core (~earth's internal structure). Its mean field intensity
at the surface is ca. 0.5 Gauss (equivalent to 50 10- 6 Tesla). At any point on the
earth, the total field intensity can be resolved in the intensity of the horizontal component and the intensity of the vertical component. The direction is
described by the deviation from the north (declination) and the angle with the
horizontal (inclination). The earth's magnetic field resembles for 90 % a
dipole field with its axis declined 11 0 from the axis of rotation. The small additional nondipole field is responsible for irregularities of the field in distribution and time (secular variation). ~magnetic anomaly and ~magnetic polarity.
magnetic anomaly any departure from the theoretical magnetic (earth) field. The
earth's magnetic field can be locally affected by induced or remanent mag-