A fault block is a large section of the Earth’s crust that has been displaced and rotated along a fault or set of faults. These blocks can be uplifted or downthrown, leading to the formation of mountain ranges, basins, and other large-scale geological features. Fault blocks are significant in tectonics, structural geology, and the study of crustal deformation.
Source Davis, G. H., & Reynolds, S. J. (1996). Structural Geology of Rocks and Regions. John Wiley & Sons.