http://anzsoil.org/def/au/asls/landform/Geomorphology-status
identifier | http://anzsoil.org/def/au/asls/landform/Geomorphology-status | |||||||||||||||||||||||||||||||
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definition | Status of geomorphological activity | |||||||||||||||||||||||||||||||
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note | It is important for theoretical and practical purposes to distinguish, if possible,
between landform patterns in which the formative geomorphological processes continue
at the present time, and those in which they are no longer active, the landform features
being relict. The problem in assigning activity status is that many processes are
episodic, so that the observation of no activity may mean that an episodic process
is in a quiescent phase. The following scale does not distinguish between processes
that operate continuously but extremely slowly and those episodic processes that are
very rare: Table 11 Typical activity status of the dominant geomorphological agent in types of landform pattern Typical activity status Landform patterns Continuously active Mountains, hills, rises, karst, coral reef Frequently active Pediment, sheet-flood fan, flood plain, bar plain, meander plain, covered plain, anastomotic plain, alluvial fan, tidal flat, dunefield, playa plain Seldom active Volcano, (lower) terrace Barely active to inactive Pediplain, peneplain, stagnant alluvial plain Relict Caldera, meteor crater, (higher) terrace, beach ridge plain, lava plain, made land Unspecified Plain, alluvial plain Table 11 shows how types of landform pattern vary in their status of geomorphological activity. Note that flood plains, including bar plains, meander plains, covered plains, anastomotic plains, and deltas, are distinguished from terraces or stagnant alluvial plains by having frequently active rather than seldom active or inactive stream flow. This may have legal significance. The frequency of occurrence of inundation (see page 96) that is classed as frequently active in this Handbook is an Average Recurrence Interval of 50 years or less. A landform pattern may change from one type to another type if the status of geomorphological activity changes for any reason, including human interference such as diverting a stream or building a dam. |
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