3.7.6 Fault block (Forkastningsblokk)
3.7.6.1 A fault block is a block of the Earth's crust formed by fault movements and which has been displaced as a single unit. It may be entirely or partially bounded by faults and can have any shape whatsoever on a map (Figs. 9, 10).
3.7.6.2 Fault block is the general designation for fault-bounded blocks of the Earth`s crust, irrespective of shape.
3.7.6.3 No limitations are placed on the dimensions of a fault block.
3.7.6.4 Fault blocks are mappable with the help of geomorphological, geological and/or geophysical methods.
3.7.6.5 An elevated fault block can give rise to a high or structural high, and a depressed fault block can form a depression or structural depression. Large fault blocks may be divided up into smaller, subsidiary ones.
3.7.6.6 A fault block can be formally or informally named 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). In the compound name, the proper name (Section 2.2.2) is placed between the words "the ... Fault Block" (formal). If there is no danger of misunderstanding the abbreviated form "Block" can be used in the compound name.
3.7.6.7 The term "fault block" is to be preferred to "horst" when an elevated fault block does not have a pronounced long, narrow shape and is not bounded by two major faults along its flanks. Borderline cases will occur.
3.7.6.8 Examples: The continental shelf contains many examples of fault blocks of various geometrical shapes. Permian fault tectonics in the Oslo Region resulted in fault blocks of various shapes.
3.7.6.9 Key reference: Bates & Jackson (1980).
