The Mid-Atlantic Ridge is the most prominent example of a divergent plate boundary where seafloor spreading occurs. As the North American and Eurasian plates move apart, magma rises from the mantle to form new oceanic crust. While other oceans have spreading centers, the Atlantic is characterized by a continuous, well-defined ridge system running through its center.

Continental crust is primarily composed of granitic rocks, which are less dense than the basaltic rocks that make up the oceanic crust. Because continental crust is less dense, it 'floats' higher on the mantle, making it effectively lighter in terms of buoyancy compared to the denser, thinner oceanic plates that sink during subduction processes.

When tectonic plates move apart at divergent boundaries, the pressure on the underlying mantle is reduced, causing partial melting. This results in the formation of magma, which rises to fill the gap. Upon reaching the surface or cooling beneath it, this magma solidifies to form new crust, effectively sealing the rift created by the diverging plates.

Subduction occurs at convergent plate boundaries where a denser oceanic plate sinks into the mantle beneath a less dense continental or oceanic plate. This process is a primary driver of volcanic activity, deep-sea trench formation, and seismic events, playing a crucial role in the Earth's tectonic cycle.

A transform plate boundary, often referred to in some contexts as a conservative or passive boundary, occurs where plates slide past each other. Unlike constructive (divergent) or destructive (convergent) boundaries, crust is neither created nor destroyed here. The friction between these plates often leads to significant seismic activity, such as the San Andreas Fault, as stress builds up and is released as earthquakes.

The collision between the South American Plate and the Nazca Plate is a textbook example of oceanic-continental subduction. The denser Nazca Plate is forced beneath the lighter South American Plate, leading to the formation of the Andes Mountains and significant volcanic and seismic activity along the western coast of South America.

Seafloor spreading occurs at mid-ocean ridges where tectonic plates move apart, or diverge. This movement creates a gap that is subsequently filled by upwelling magma, which cools to form new oceanic crust, effectively widening the ocean basin over geological time.

Divergent plate boundaries occur when two tectonic plates move away from each other. As the plates separate, magma from the mantle rises to fill the gap, cooling to create new crust. This process is responsible for the formation of mid-ocean ridges and rift valleys. It is a fundamental concept in plate tectonics that explains the continuous renewal of the Earth's surface and the expansion of oceanic basins.

Mid-ocean ridges are continuous mountain ranges formed on the ocean floor at divergent plate boundaries. As tectonic plates move apart, magma rises from the mantle to create new oceanic crust, forming these underwater ridges.

California is home to the San Andreas Fault, which is a transform plate boundary where the Pacific Plate and the North American Plate slide horizontally past each other. This tectonic activity is responsible for frequent seismic events in the region, making it a primary site for studying transform plate movements.