Lithospheric plates are massive, rigid slabs that make up Earth's outer shell. The lithosphere, consisting of the crust and uppermost mantle, is broken into these large pieces that float and move slowly over the semi-fluid asthenosphere beneath. These plates include both oceanic and continental types, each with different densities and characteristics.
There are three main types of plate boundaries where different geological processes occur. Divergent boundaries occur where plates move apart, creating new oceanic crust. Convergent boundaries form where plates collide, often creating mountains or deep ocean trenches. Transform boundaries develop where plates slide past each other horizontally, frequently causing earthquakes.
Lithospheric plates move due to several driving forces. The primary force is mantle convection, where hot material rises and cool material sinks, creating circular currents. Ridge push occurs at divergent boundaries, while slab pull happens at convergent boundaries. These plates move very slowly, only two to ten centimeters per year, but this continuous movement over millions of years reshapes our planet's surface.
Earth's lithosphere consists of several major plates of varying sizes. The largest include the Pacific Plate, which is mostly oceanic, and the North American, Eurasian, African, Antarctic, Indo-Australian, and South American plates. These plates differ dramatically in size and composition. Some are purely oceanic, others purely continental, but most major plates contain both oceanic and continental crust, making them mixed-type plates.
To summarize what we have learned about lithospheric plates: They are massive rigid slabs that form Earth's outer shell and move slowly over the asthenosphere. The three types of plate boundaries create earthquakes, volcanoes, and mountains. Mantle convection provides the driving force for this continuous movement that reshapes our planet over geological time.