Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core. The plates act like a hard and rigid shell compared to Earth's mantle. This strong outer layer is called the lithosphere.
The theory states that Earth's outermost layer, the lithosphere, is broken into 7 large, rigid pieces called plates: the African, North American, South American, Eurasian, Australian, Antarctic, and Pacific plates. Several minor plates also exist, including the Arabian, Nazca, and Philippines plates.
The plates are all moving in different directions and at different speeds (from 2 cm to 10 cm per year--about the speed at which your fingernails grow) in relationship to each other. The plates are moving around like cars in a demolition derby, which means they sometimes crash together, pull apart, or sideswipe each other.
The place where the two plates meet is called a plate boundary. Boundaries have different names depending on how the two plates are moving in relationship to each other.
- crashing: Convergent Boundaries,
- pulling apart: Divergent Boundaries,
- or sideswiping: Transform Boundaries
Boundaries in Action
Research
With respect to plate boundaries is your home located in the middle of, or near the boundary of a plate? What does this mean for you tectonically?
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