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stratigraphy
straddling stocks fish stocks that migrate between exclusive economic zones and
the high seas.
strain a population of cells all descended from a single cell; a clone.
strait -tchannel.
stratification (in the seawater column) the occurrence of more or less horizontal
water layers in the sea as a consequence of differences in density [Le., in
salinity ( -thalocline) or temperature (-tthermocline) J. The persistence of stratification depends on the static stability of the stratified water column. The
water is stable if a parcel of water, moved from its original level, experiences
a gravitational force that drives it back to its original depth, and unstable if
the gravitational force moves it further away (-tconvection). The stability
depends on the degree of increase of density with depth at a given location.
The larger the stability, the more energy is required for vertical mixing of the
water column. In internal waves the restoring force that makes the water elements oscillate, and the maximum limiting value of internal wave frequency,
the Brunt-Vaisala frequency, depend on the stability. In the upper layers of the sea
the often observed form of stratification is one marked by a sudden decrease
of temperature with depth (thermocline). Here the stability is large and vertical
mixing is difficult, so a thermocline may persist for long periods.
stratigraphic correlation determination of stratigraphic relation between different rock units, based on geologic age (time of formation), lithologic characteristics, fossil content, or any other property. The term almost always denotes
time correlation. -tstratigraphy.
stratigraphic hierarchy the nomenclature of stratigraphic units depends on the
type of stratigraphy used. There is a stratigraphic hierarchy in the names
arranged below in order of magnitude. Chronostratigraphical terms are
time-rock terms. Bio-, litho-, and magnetostratigraphical terms are not strict1y equivalent to geochronological terms and are therefore placed separately.
Bio-, chemo- and magnetostratigraphic units (in the chronostratigraphical sense)
are referred to as zones, and their geochronological equivalents are chrons.
Prefixes super- and sub- can be added for further subdivision.
stratigraphy study of layered rocks (sediments and volcanics), especially their
sequence in time, the character of the rocks and the correlation of beds in
different localities (-tstratigraphic correlation). Stratigraphy distinguishes units
and boundaries based on a number of different aspects: form, distribution
and lithologic composition of the beds (lithostratigraphy), their fossil content
(biostratigraphy), and geophysical and geochemical properties, such as the succession of intervals of remanent magnetism (magnetostratigraphy), the ratios of
stratigraphy
straddling stocks fish stocks that migrate between exclusive economic zones and
the high seas.
strain a population of cells all descended from a single cell; a clone.
strait -tchannel.
stratification (in the seawater column) the occurrence of more or less horizontal
water layers in the sea as a consequence of differences in density [Le., in
salinity ( -thalocline) or temperature (-tthermocline) J. The persistence of stratification depends on the static stability of the stratified water column. The
water is stable if a parcel of water, moved from its original level, experiences
a gravitational force that drives it back to its original depth, and unstable if
the gravitational force moves it further away (-tconvection). The stability
depends on the degree of increase of density with depth at a given location.
The larger the stability, the more energy is required for vertical mixing of the
water column. In internal waves the restoring force that makes the water elements oscillate, and the maximum limiting value of internal wave frequency,
the Brunt-Vaisala frequency, depend on the stability. In the upper layers of the sea
the often observed form of stratification is one marked by a sudden decrease
of temperature with depth (thermocline). Here the stability is large and vertical
mixing is difficult, so a thermocline may persist for long periods.
stratigraphic correlation determination of stratigraphic relation between different rock units, based on geologic age (time of formation), lithologic characteristics, fossil content, or any other property. The term almost always denotes
time correlation. -tstratigraphy.
stratigraphic hierarchy the nomenclature of stratigraphic units depends on the
type of stratigraphy used. There is a stratigraphic hierarchy in the names
arranged below in order of magnitude. Chronostratigraphical terms are
time-rock terms. Bio-, litho-, and magnetostratigraphical terms are not strict1y equivalent to geochronological terms and are therefore placed separately.
Bio-, chemo- and magnetostratigraphic units (in the chronostratigraphical sense)
are referred to as zones, and their geochronological equivalents are chrons.
Prefixes super- and sub- can be added for further subdivision.
stratigraphy study of layered rocks (sediments and volcanics), especially their
sequence in time, the character of the rocks and the correlation of beds in
different localities (-tstratigraphic correlation). Stratigraphy distinguishes units
and boundaries based on a number of different aspects: form, distribution
and lithologic composition of the beds (lithostratigraphy), their fossil content
(biostratigraphy), and geophysical and geochemical properties, such as the succession of intervals of remanent magnetism (magnetostratigraphy), the ratios of