1. The ability to separate two features that are close together. The minimum separation of two bodies before their individual identities are lost on the resultant map or cross-section. See resolvable limit and Sheriff and Geldart (1995, 172–177). 2. The smallest change in input that will produce a detectable change in output. (See Figure D-8 for the vertical resolution of logging tools.) 3. The ability to localize an event seen through a window, usually taken as the half width of the major lobe.