If geological these are usually faults, joints, or boundaries between stratigraphic formations. Examples are shown. Lineaments and Fractures We turn now to lineaments. In the early days of Landsat, perhaps the most commonly cited use of space imagery in Geology was to detect linear features that appeared as tonal discontinuities. Almost anything that showed as a roughly straight line in an image was suspected to be geological.
Lineaments are well-known phenomena in the Earth's crust.
Rocks exposed as surfaces or in road cuts or stream outcrops typically show innumerable fractures in different orientations, commonly spaced fractions of a meter to a few meters apart. These lineaments tend to disappear locally as individual structures, but fracture trends persist. The orientations are often systematic meaning, that in a region, joint planes may lie in spatial positions having several limited directions relative to north and to horizontal. Obviously, some of these features are not geological. Instead, these could be fence lines between crop fields, roads, or variations in land use.