Þingvellir – contintents breaking apart
It is well known that Iceland has one of the most fascinating and unique geological settings on earth. The island lies on top of a hot spot (stationary plume of magma) as well as on the Mid-Atlantic Ridge. The combination of these two features caused excessive volcanic eruptions. As the plates moved apart a continuous flow of lava was pushed out from underneath the earth’s crust. It eventually breached the surface of the sea and created the island of Iceland.
The plate motion produced several formations which allow us to see the effects of the North American and Eurasian Plates drifting apart. It can be best observed in the famous Þingvellir National Park (pronounced „thinkvetlir“) displaying a rift, which has produced dramatic fissures and cliffs on both sides of the valley.
The national park is enclosed on three sides by mountains and on the southern side by Iceland’s biggest lake called Þingvallavatn. The lake is very deep and with its maximum depth of 114 meters it even descends about 10 meters below the present sea level. It originated as a glacial lake about 10 000 years ago. Its size and shape was changed because of three big volcanic eruptions which filled the valley with lava. The lava leads to a high uptake of minerals in the groundwater and this is one of the reasons for the great diversity of life in the water. It also creates many hideouts and holes for animals in the lake, as well as along its shore.
The major feature of the park, however, is the graben running along the valley. It is characterized by blocks stepping towards the east on the west side (North American plate), while the situation is reversed on the east side (Eurasian plate). These almost parallel faults on both sides of the valley are deeply rooted, sometimes filled with crystal clear water and can cause occasional earthquakes in the area.
The floor of the valley is a linear block that has subsided as the plates were pulled away from each other. Currently the walls are moving apart at a rate of about 7 mm per year and the floor is subsiding at about 1 mm per year.
The Þingvellir National Park was designated a UNESCO World Heritage Site on cultural criteria because it hosted one of the first democratic assemblies ever, called the “AlÞing”. It was established in 930 and continued until 1798 in this very special location. During the AlÞing laws were proclaimed, charges made and verdicts announced. Remains from the assembly can still be seen in the national park.
All these factors make Þingvellir a site of historical, cultural, and geological importance and one of the most popular tourist destinations. Together with waterfall Gullfoss and the geysers it is part of a group of the most famous sights of Iceland, the Golden Circle.
Image credits: http://bit.ly/1R9btda http://bit.ly/1P9IK1L Sources: http://www.thingvellir.is/english/ http://whc.unesco.org/en/list/1152 http://bit.ly/1YPcQ4Z