4.1: Tectonic Plates

Convergent Boundaries

At a convergent boundary, two tectonic plates are moving towards each other ( -> <- ). Typically, at these boundaries, subduction takes place as the tectonic plate that is more dense moves under the plate that is less dense. An example of a convergent boundary is the Mariana Trench.

These converging plates can be between two oceanic plates or a continental and oceanic plate. Depending on the plates that are converging, different structures can form. Between oceanic plates, it is more likely for island arcs, oceanic trenches, and volcanoes to form. Between an oceanic plate and continental plate, it is likely for mountains and volcanoes to form.

Divergent Boundaries

At a divergent boundary, two tectonic plates are moving apart from each other ( <--> ). This can create visible fault lines, rift valleys, seafloor spreading, volcanoes, and earthquakes. A few examples of divergent boundaries are the East Africa Rift Valley, Mid-Atlantic Ridge, and the East Pacific Rise.

Seafloor spreading is a process that takes place at divergent boundaries on the ocean floor. As the two tectonic plates move apart from each other, magma is able to go up through the space between the plates. The cool ocean water cools it down and more rock forms.

Transform Boundaries

At a transform boundary, two tectonic plates slide past each other 🔼🔽. This often causes earthquakes. As the plates slide past each other, friction and energy build up. When this heat/energy is released quickly, an earthquake results. An example of a transform boundary is the San Andreas Fault in California.

Plate Tectonics Map

By analyzing maps of tectonic plates and the landforms that occur there, geologists can better understand tectonic plate movements. For example, we can better understand the volcanoes and plate tectonics by looking at the Ring of Fire in the Pacific Ocean and the plate movements that cause it. We can also predict optimal ways for natural disaster prevention by understanding where and when a certain fault line event is possible.