In geology, a joint is a fracture dividing rock into two sections that have not moved away from each other. A joint does not involve shear displacement, and forms when tensile stress breaches its threshold. In other kinds of fracturing, like in a fault, the rock is parted by a visible crack that forms a gap in the rock.
Joints push out in various directions, usually vertically. They can have smooth, clean surfaces, or they can be scarred from sliding against another joint. Joints usually occur as sets, with each set made up of joints that are parallel to each other.
References[change | change source]
- Engelder, T. & Geiser, P. 1980. On the use of regional joint sets as trajectories of paleostress fields during development of the Appalachian Plateau, New York. Journal of Geophysical Research, 85, B11, 6319-6341.
- "Joint (geology)". Britannica Online. Encyclopaedia Britannica. Retrieved 15 March 2012.