The Mid-Atlantic Ridge is a submarine ridge located along the floor of the Atlantic Ocean, that wraps around the globe for more than 65,000 km like the seam of a baseball. It is the longest and the most extensive chain of mountains on earth, but being located underwater, more than 90% of this mountain range remains hidden from view. There are only a few places on earth where it juts out of the surface of the ocean, in the form of a few islands, one of which is Iceland.
Iceland represents the largest portion of the mid-Atlantic ridge exposed above sea level. Formed from volcanic eruptions on the Mid-Atlantic ridge, about 24 million years ago, it is one of the few places where you can stand on the ridge on dry land. This makes Iceland very special and a popular place for geologists and scientists.
This is the Mid-Atlantic Ridge. A visitor stands between the two tectonic plates. Photo credit
The Mid-Atlantic Ridge is geologically significant because it marks the boundary where the North American and Eurasian tectonic plates meet and separate. Volcanic eruptions at this boundary create new ocean floor and at the same time push the two tectonic plates apart at rates of 1 cm to 20 cm per year, a process known as sea-floor spreading. As oceanic plates move apart, rock melts and wells up from tens of kilometers deep producing enormous volcanic eruptions of basalt, and building the longest chain of volcanoes in the world.
The place where the Mid-Atlantic Ridge is best visible is at Thingvellir National Park, in southwestern Iceland. The continental drift between the North American and Eurasian Plates can be clearly seen in the cracks or faults which traverse the region, the largest one, Almannagjá, being a veritable canyon.
The section of the ridge that includes the island of Iceland is known as the Reykjanes Ridge. The ridge is spreading at an average rate of about 2.5 cm per year. Over the past 10,000 years the Thingvellir Rift Valley has widened by 230 feet (70 m) and sunk by 131 feet (40 m). Not only is the mid-ocean ridge changing the geography of Iceland, it’s also responsible for the volcanic activity which created the island. As the two tectonic plates shift, fissures periodically form in the crust that allow molten rock from underground to surface as lava, creating Iceland's many volcanoes. Iceland is one of the most geologically active places on Earth with more than 15 volcanoes that have erupted in the last century.
Map of the Mid-Atlantic Ridge, running from top to bottom, between the continents of North/South America and Africa.
Visitors walking next to the North American plate. On the right is the Eurasian plate. Photo credit
Visitors walking next to the North American plate. Photo credit
The American plate on the left and the European plate on the right. A boardwalk was constructed at this park for visitors to walk down the middle. Photo credit
The Silfra fissure, a popular dive and snorkel tour location, is also located within Thingvellir National Park on the northern shore of Thingvallavatn, the largest natural lake of Iceland. Here tourists, donning scuba gear, can dive between the two tectonic plates. Photo credit
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