archipelagos
How they are formed
Volcanoes from the ocean floor created archipelagos. The Earth’s crust shifted while the hot spot stayed put, creating a line of islands that show exactly the direction the crust moved.The largest archipelago in the world was formed by glacial retreat Malay archipelago between the Pacific and Indian Oceans, contains more than 25,000 islands in Southeast Asia. The most common way archipelagos are formed is through volcanic activity combined with tectonic movement. When underwater volcanoes allow magma to seep out in the sea rock formations are made under the water. As more magma is released the rock formations eventually peak out over the surface of the water, creating an island. Some of these islands sometimes have volcanoes. The Hawaiian Islands are an example of an archipelago with volcanic origin that still has active volcanoes.
OTHER CAUSES
Volcanic activity is most conman formation of many large island chains in the sea, some archipelagos have other ways of being formed. Mountains are formed when tectonic plates collide and push each other up in the air. Tectonic plates under the sea may cause mountains to rise up from the sea and create islands. Sea level is another important factor in the formation of archipelagos. If the sea level were to fall or rise, some islands would be created while others would disappear. For instance, if the ice caps were to melt extensively because of global warming, the rise in sea level might form new archipelagos along the coastal terrain, while existing islands might disappear.