A transform plate boundary is a kind of horizontal fault which cuts through the entire lithosphere, often causing folding, faulting and uplifting of nearby rocks. Joint Structures A joint is a fracture similar to a fault but without the rocks on opposite sides moving. They often occur in two sets of cracks intersecting between 45-90 degrees, dividing the rocks into rectangular blocks. Columnar joints can be formed when hot basalt cools and shrinks. Parallel joints are caused by tectonic forces sufficient to fracture the rock but not to move it.
Joints are places of weakness in otherwise strong rock.
As such, engineers, miners, and quarry operations tend to be aware of them. A dam constructed in jointed rock will leak because the water will seep into the joints and flow through the fractures to the side where it's not wanted. References Dennis, John G. Structural Geology . The Ronald Press Company, New York, New York. Thompson, Graham R. and Jonathan Turk.