3.7.11 Platform (Plattform)
3.7.11.1 A platform is a geomorphological and/or structural form element which consists of a flat, tectonically relatively stable area. The even surface of the platform is formed by erosion and/or deposition. A platform is delimited on one or more sides by contemporaneous, lower-lying areas (Figs. 9, 10).
3.7.11.2 A platform is a form element which, as regards height, is located between a high and a depression (Fig. 8).
3.7.11.3 A platform is a regional-sized feature; subtypes may be local in extent (Section 3.7.11.7).
3.7.11.4 A platform is mappable with the help of geomorphological, geological and/or geophysical methods.
3.7.11.5 A platform may often be divided into several geomorphological and/or structural form elements.
3.7.11.6 A platform can be given a formal or an informal name 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 ... Platform" (formal) in the compound name.
3.7.11.7.a Platform morphology includes all types of terrace. The term terrace (terrasse) comprises a long, narrow terrace surface which usually slopes gently downwards towards an outer edge where it is bounded by a terrace brink or terrace edge and a steeper terrace slope towards a depression. On the inner side, the terrace surface is bounded by a corresponding steeper slope towards a high. "Terrace" has been used for both the terrace surface itself and the terrace slope, and should also include the brink or edge between them (see escarpment, Section 3.7.12). "Platform slope" and "platform brink" or "edge" are used in a corresponding manner to "terrace slope" and "terrace brink" (Figs. 9, 10).
3.7.11.7.b A marine terrace (marin terrasse) is a terrace built up towards the current sea level by deposition of superficial deposits, and/or cut by wave erosion in bedrock or superficial deposits.
3.7.11.7.c A raised beach terrace (strandterrasse) is a narrow terrace representing a former marine or lacustrine shore zone.
3.7.11.7.d A kame terrace, ice-contact terrace or valley-side terrace (kameterrasse, iskontaktterrasse, dalsideterrasse) largely consists of water-transported material piled up along the side of a valley glacier. The terrace slope may have originated as an ice-support contact, an erosion surface, or as a combination of both mechanisms.
3.7.11.7.e A shoreline is the line of intersection between land and sea, or between land and a lake. Levels of former shorelines (strandlines, strandlinjer)) can be defined by a raised beach terrace, a raised beach ridge, an erosion notch in bedrock or superficial deposits (a shore notch) and a delta surface. Former shoreline levels may also be defined litho- and biostratigraphically.
3.7.11.7.f Terraces and shoreline levels can be given formal or informal names, and can provide a basis for morphostratigraphical classifications (Section 3.10, Fig. 26).
3.7.11.8 Example: The Trøndelag Platform (Gabrielsen et al. 1984) is one of several structural platforms on the Norwegian continental shelf.
3.7.11.9 Key reference: Bates & Jackson (1980).
