About Archipelagos
An archipelago is a group of islands, congregated in the same geographical area, that share a common origin. Archipelagos are common features in the oceans as well as in many lakes. Many well-known island chains are archipelagos, such as the Hawaiian Islands, the Aleutian Islands and the Philippines. Like mountains and other land formations, archipelagos are formed in part by tectonic activity--the movement of the large plates that make up the Earth's crust--but other factors can also affect the formation of archipelagos.
Volcanic Formation
The most common way archipelagos are formed is through volcanic activity combined with tectonic movement. When underwater volcanoes, or hot spots, allow magma (liquid rock) to seep out in the sea, rock formations are created under the water. As more and more magma is released, the rock formations eventually peak out over the surface of the water, creating an island. Since tectonic plates shift over time, the magma leakage from the hot spots shifts, which can lead to the formation of many islands within a relatively small area. Some of these islands are also likely to have volcanic activity or inactive volcanoes. The Hawaiian Islands are an example of an archipelago with volcanic origin that still has active volcanoes.
Other Causes
While volcanic activity is the cause for the formation of many large island chains in the sea, some archipelagos have other origins. 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.
Tags: volcanic activity, archipelagos formed, formation archipelagos, formation many, Hawaiian Islands, island chains, rock formations
