A tectonic plate(or lithospheric plate or crustal plate) is a slab or irregularly shaped solid rock, generally composed of both continental or oceanic lithosphere. Tectonic plates can vary greatly in size. From a few thousand kilometers to a few hundred. Plate thickness can also vary, from fifteen kilometers for oceanic tectonic plates to two hundred for continental plates. Tectonic plates are always moving. That’s why 250 million years ago, the world looked completely different.
Divergent boundaries are where the two plates are moving away from each other
Convergent are when they are moving towards each other. One of the plates is forces under the other.
Transform boundaries are where the two plates are rubbing against each other.
| Oceanic | Continental |
|---|---|
| Formed from divergent boundaries. | Formed from oceanic-continental boundaries, the oceanic plate subducts. |
| More dense | Less dense |
| Young(no more than 200 million) | Old(no less than 1 billion) |
| Thinner(4-5 miles) | Thicker(50 miles) |
| 71% of earth’s crust | 29% of earth’s crust |