3.7.13 Depression, Low (Senkning, Søkk)
3.7.13.1 A depression is a present-day or former, negative landform and/or a structural feature of non-specified origin and shape. A low is (a) a negative structural feature of non-specified origin and shape, or (b) a negative geophysical anomaly (Figs. 9, 10).
3.7.13.2 Depression is a general term for a low-lying geological or geomorphological feature which is usually entirely surrounded by higher ground. Low is a corresponding general term used in a structural context and to characterize a negative geophysical anomaly. Elongate depressions or lows may be open at one or both ends.
3.7.13.3 No limitations are placed on the dimensions of depressions or lows.
3.7.13.4 The structures are mappable with the help of geomorphological, geological and/or geophysical methods.
3.7.13.5 Depressions and lows will often be divisible into smaller geomorphological and structural features, or smaller geophysical anomalies.
3.7.13.6 Depressions and lows may be given formal or informal names in accordance with the "general rules for naming and defining geological units" (Chap. 2) and the rules for naming geological form units (Section 3.7.1). A proper name (Section 2.2.2) is placed between the words "the ... Depression" or "the ... Low" (formal) in the compound name. The type of data used as the basis for the designation can be indicated by inserting an adjective such as "gravimetric" or "magnetic" before "low". If a depression or low is known to have a structural origin, this can be conveyed by writing "structural depression" or "structural low".
3.7.13.7.a Depressions or lows may be parts of larger geomorphological, structural or geophysical features. They enjoy a corresponding status among negative features to that held by highs among positive ones. A structural depression or low need not be, or have been, expressed geomorphologically.
3.7.13.7.b The term caldera (kaldera) is used for a circular or oval, volcanic depression whose diameter is substantially larger than its depth.
3.7.13.8 Examples: The general term "depression" can be used for all large and small negative landforms and large ocean basins. Examples of named continental depressions are the Qattar Depression in Egypt and the Turfan Depression in Sinkiang in western China.
3.7.13.9 Key references: Gjessing (1978), Bates & Jackson (1980).
