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In the previous video you have already seen what happens at a convergent plate boundary when an oceanic plate is involved; one plate will dive below the other and there is subduction. This video explains what happens when two continental plates collide. Suppose; there is a subduction zone where an oceanic plate dives below a continental plate. The rest of the plate is also pulled by the slab pull. It may happen that there is both oceanic and continental crust on that plate. Due to the movement of the plate, the continental crust also arrives at the subduction zone. Now two continental plates collide. Both plates are lighter than the underlying asthenosphere. As a result, there is little or no subduction. The plates are pushed together and fold. Sometimes you can clearly see that the rock has been compressed . A high mountain range is created by folding. This high mountain range is called an orogenic belt. But not only the top of the crust is folded. The continental crust also gets much thicker at the bottom. That is because the crust floats on the asthenosphere. In an earlier video this has already been compared to an ice cube. The larger the ice cube, the more ice there is also under water. The same applies to the crust: the higher the mountains, the larger the part of the crust that is in the asthenosphere. The crust under a mountain range is therefore very thick, up to a maximum of about 80 kilometers! Just like a convergent zone in which an oceanic plate is involved, there can also be very serious earthquakes at this plate boundary. But because there is no subduction, there are no volcanoes! The African plate and the Indian plate move north against the Eurasian plate. Because of this convergent movement, many mountains have been formed from Morocco to India, including the Alps and the Himalayas. This movement to the north started about 60 million years ago. All these mountain ranges were therefore created in the same era. The mountain formation in this period is also called the alpine orogeny. Orogeny means mountain formation. The term alpine orogeny therefore means a geological period in which all of these mountains originated. There have also been earlier periods in which mountain ranges were formed. For example, the Ardennes and the Scottish Highlands were formed during these periods. Due to erosion and weathering, the Ardennes were partly tore down. Other mountain ranges have even disappeared completely! In this video you have seen that with a convergent plate boundary in which only continental plates are involved, mountain ranges are created. There are also heavy earthquakes. However, unlike a convergent plate boundary involving an oceanic plate, there are no volcanoes.
