In geology and geomorphology, a tessellated pavement is a relatively flat rock surface that is subdivided into polygons by fractures, frequently systematic joints, within the rock. This type of rock pavement bears this name because it is fractured into polygonal blocks that resemble tiles of a mosaic floor, or tessellations.
A tessellated pavement at Eaglehawk Neck, Tasmania, where a rock surface has been divided by fractures, producing a set of rectangular blocks
Sunrise on the tessellated pavement at Eaglehawk Neck, Tasmania, illustrating the pan formation of tessellation
A joint is a break (fracture) of natural origin in a layer or body of rock that lacks visible or measurable movement parallel to the surface (plane) of the fracture. Although joints can occur singly, they most frequently appear as joint sets and systems. A joint set is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A joint system consists of two or more intersecting joint sets.
Horizontal joints in the sedimentary rocks of the foreground and a more varied set of joints in the granitic rocks in the background. Image from the Kazakh Uplands in Balkhash District, Kazakhstan.
Orthogonal joint sets on a bedding plane in flagstones, Caithness, Scotland
Joints in the Almo Pluton, City of Rocks National Reserve, Idaho.
A rock in Abisko fractured along existing joints possibly by mechanical frost weathering
