Subduction: This is the process that takes place at convergent boundaries. One tectonic plate moves under another tectonic plate, and sinks into the mantle.
ocean to ocean- one of the plates is subducted under the other during the collision, similar to oceanic-continental. The crust that is pulled under or subducted, melts to form magma. Then it rises to the top of the overriding oceanic plates, and erupts on the ocean floor.
ocean to continental- When an oceanic plate collides with a continental plate the crust forms oceanic plates that get bent and pulled under the continental crust. The rocks that form the oceanic crust are denser and thinner than the rocks that formed. The process by the oceanic crust is pulled under the continental crust, called subduction.- zone where the oceanic crust sinks beneath the continental crust creating oceanic trench or valleys.
continental to continental- When two continental plates collide they resist downwards motion because the continental rocks that make them up are similar in density. The crust will (tends) to buckle and gets pushed upwards and sideways. Causing the two continental plates to form a mountain by their collision.
ridge (ocean)- Divergent boundaries in the middle of the oceans cause seafloor spreading. As oceanic plates move apart they produce cracks in the ocean floor. Magma rises up from the mantle and out from the cracks. Eventually the cooling magma piles up to form a ridge called a mid-ocean ridge.
rift (land)-A rift is a dropped zone at the point where the plates are moving apart. As the plates start moving away from each other, the crust widens and thins. Then valleys and volcanoes begin to form in and around the area.The width of the crust along boundary becomes so thin, that a piece of continent can break off to form a new tectonic plate.
This is where two of the tectonic plates, side alongside each other. In transform boundaries, no new crust is created, and there is no subduction. When this happens, the rubbing of the two plates causes earthquakes. It also might observe linear valleys, where rock has been broken down to leave gaps.