What Do Transform Boundaries Form?Īs mentioned above, fault geometry plays a big role in forming topography along transform boundaries. Below we’ll describe some of these features in more detail and take a look at some examples of transform boundaries from different locations around the world. Mountains, basins and unique topography can form along transform boundaries depending on the fault’s geometry, the rock type and how parallel the motion of the plates are to the strike of the fault. Earthquakes associated with transform boundaries are relatively shallow occurring at depths of ~0-20 km beneath the surface. Like all plate boundaries, the movement of crust along transform and strike-slip faults creates earthquakes. Transform boundaries also form on larger scales on land like the San Andreas fault in Western North America and the Alpine fault in New Zealand. As shown in the map below, they are particularly common along divergent plate boundaries where they connect sections of oceanic spreading centers or mid-ocean ridges, helping create some of the longest topographic features on the planet. Transform boundaries occur all over the world and come in many shapes and sizes. Similarly, if the same situation occurred and the fault was left-lateral, the tree would move left. As shown below, a person standing on one side of a right-lateral strike-slip fault will watch a tree on the opposite side move right as the fault slips. Transform boundaries can be dextral (right-lateral) or sinistral (left-lateral) with fault planes near vertical or dipping steeply in one direction. Instead, due to the relative motion of the plates being parallel to and in opposite directions across the fault, the plates slide past each other laterally. Unlike divergent (constructive) and convergent (destructive) plate boundaries, lithosphere at transform boundaries is neither created nor destroyed deeming them “conservative” plate boundaries. Transform boundaries occur where the Earth’s tectonic plates slide past each other horizontally along transform or strike-slip faults.