Convergent Boundaries
There is nothing proving that the earth has gotten bigger over the years. So one of the theories we have come up with prove that all old crust is recycled at the same place new crust is made. This crust is recycled at boundaries where the plates move closer to each other. These boundaries are called Convergent Boundaries.
There are three types of convergent boundaries.
1. Oceanic-Continental
2. Oceanic-Oceanic
3. Continental-Continental
Certain types of plates coming together create the different boundaries.
Oceanic-Continental
This type Convergence happens when an Oceanic Plate collides with a Continental Plate. As a result, the oceanic plate will slide under the Continental Plate. There will also be a deep trench where the plates collide.
An example of this is on the coast of BC the oceanic plate slid under the North American continental plate creating a trench.
Oceanic-Oceanic
This type of convergence is almost the same as the first type. When two oceanic plates come in contact with each other the older, colder, thicker plate curves lower into the mantle. Like oceanic- continental convergence, oceanic- oceanic convergence makes trenches deep down in the water.
Continental Convergence
This type of convergence occurs when two continental plates collide with each other. The plates push against each other until the plates are forced together and upwards creating land formations like mountains on Earth's surface.
An example of this is the Himalayan Mountains. About 50 million years ago, the Indian Plate collided with the Eurasian Plate. The plates pushed against each other and forced each other upwards. Over the slow process of convergence of the two plates, they now reach their present height today.