Iceland is the remains of a sunken continent
Iceland may not have been formed by volcanoes. Geologists now suspect that it is the tip of a flooded continent.
Iceland may not be a volcanically-formed island, as generally believed. A new book by geophysicist Gillian R. Foulger and her colleagues from Durham University in the UK suggest instead that the island could be the tip of a sunken continent. The theory would explain why the crust below Iceland is much thicker than it should be had the island had formed in volcanic eruptions.
Iceland is located where two tectonic plates are moving away from each other, and hot magma flows out of underground volcanoes.Small volcanic islands sometimes emerge in the waters off the main island, so the idea that the entire land mass is also the result of volcanic activity has seemed an obvious conclusion. However, important evidence indicates that Iceland is indeed the remains of a continent. The tectonic plates – or the geological crust – under Earth’s oceans are typically 6-7km thick, but they are much thicker below the continents: 35-70km. Below Iceland, the crust thickness is about 40km, so much more like continental crust than ocean crust. Geologists have previously explained the thick crust with the fact that Iceland is located in a geological hot spot, in which intense volcanic activity forms new crust very quickly. But Foulger does not believe this theory. The crust is simply too thick to be explained by the volcanic theory.
Instead, she thinks that Iceland is the tip of a continent which stretched across 600,000km2 of the North Atlantic – the ancient continent of Islandia. According to Foulger, Islandia once formed part of the supercontinent of Pangaea some 175 million years ago. As America and Europe pulled away from each other, Islandia’s continental crust sank and was covered in water, leaving only Iceland above water today. Foulger now aims to search the Icelandic underground for minerals that can reveal if Islandia actually existed.
If the continent theory proves correct, it is not only of interest to geologists. It could affect claims of ownership over under-sea oil and natural gas deposits.