In
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, a sequence is a
stratigraphic unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it ...
which is bounded by an
unconformity
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...
at the top and at the bottom.
Definition
In a more rigorous and general way a sequence is defined as a
"relatively conformable
.. genetically related succession of strata bounded by unconformities or their correlative surfaces"
Special cases and related concepts
Special cases of sequences include
type 1 sequence In sequence stratigraphy, a sub discipline of geology, type 1 sequences and type 2 sequences are special sequences
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, i ...
s and
type 2 sequence In sequence stratigraphy, a sub discipline of geology, type 1 sequences and type 2 sequences are special sequences
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, i ...
s.
A related concept are
parasequence A parasequence is a fundamental concept of sequence stratigraphy. Parasequences are not directly related to sequences.
Definition
A parasequence is defined as a genetically related succession of bedsets that is bounded by marine flooding surfaces ...
s. Contrary to their name they are not smaller sequences.
See also
*
Catena (soil)
A catena in soil science (pedology) is a series of distinct but co-evolving soils arrayed down a slope. Each soil type or "facet" differs somewhat from its neighbours, but all occur in the same climate and on the same underlying parent material. A ...
References
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Sequence stratigraphy
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