Final answer:
When two continental masses are moving on a collision course, they can buckle and fold, forming mountain ranges. In some cases, the area beside the continental collision may form a shallow inland ocean. When plates come together, one plate may be forced beneath another in a subduction zone. The thinner oceanic crust can be subducted and recycled into the mantle, resulting in island arcs and continental fragments becoming sutured onto continents.
Step-by-step explanation:
When two continental masses are moving on a collision course, they push against each other under great pressure. Earth buckles and folds, dragging some rock deep below the surface and raising other folds to heights of many kilometers. This is the way many, but not all, of the mountain ranges on Earth were formed. If the area beside the continental collision is wide, it will form a shallow inland ocean, such as Baffin Bay in northern Canada. As new crust is added to Earth, the old crust must go somewhere. When two plates come together, one plate is often forced beneath another in what is called a subduction zone. In general, the thick continental masses cannot be subducted, but the thinner oceanic plates can be rather readily thrust down into the upper mantle. When oceanic crust is subducted, it can melt and be recycled into the mantle through convection currents. These processes can result in island arcs and continental fragments becoming sutured onto continents.