Plate tectonics is a widely held scientific idea that the Earth's lithosphere is made up of a number of huge tectonic plates that have been moving slowly since around 3.4 billion years ago. The lithosphere of Earth, which consists of the planet's solid outermost shell (the crust and upper mantle), is divided into seven or eight major plates (depending on how they are classified) and several minor plates. The type of boundary is determined by the relative motion of the plates where they meet: convergent, divergent, or transform. Along these plate borders, earthquakes, volcanic activity, mountain-building, and oceanic trench development occur (or faults). The plates' relative movement normally ranges from zero to ten centimeters every year. The oceanic lithosphere and the thicker continental lithosphere, each topped by its own type of crust, make up tectonic plates. The study of the three-dimensional distribution of rock units in relation to their deformational histories is known as structural geology. The major purpose of structural geology is to use measurements of today's rock geometries to learn more about the history of deformation (strain) in the rocks and, in turn, to comprehend the stress field that caused the observed strain and geometries. This knowledge of stress field dynamics can be related to significant geologic events; a typical goal is to comprehend the structural evolution of a specific area in relation to regionally extensive patterns of plate tectonic rock deformation (e.g., mountain building, rifting).