Iceland Adventure with Blue Green Expeditions
About 150 million years ago, the tectonic plates started moving apart while lava was pushing out from underneath Earth’s crust and flowing out in the Atlantic Ocean. As the water was cold, the lava solidified as another continuous flow of magma from the heart of the Earth pushes the hard lava higher, forming the Mid-Atlantic Ridge and later on, the island of Iceland.
Iceland is divided by the Mid-Atlantic Ridge, some parts of the country are on the North American plate while others are located on the Eurasian plate. It is the only country in the world where this rift happens to be above the sea level. The Mid-Atlantic Ridge can clearly be seen in Thingvellir National park, with the Almannagjá canyon. The huge rocky walls, which actually are the edges of the tectonic plates, rise up high from the ground. The continental plates are still moving apart by approximately 2 centimeters (1 inch) per year. Over the past 10,000 years, Thingvellir Rift Valley has gained 70 meters (230 feet) width and 40 meters (131 feet) depth.
Many fissures including Silfra opened up in 1789 due to earthquakes along with the divergent movement of the plates. Since then, many changes have occurred in Silfra with each earthquake results in rocks falling into the crack and collapsing. They can get stuck in narrow sections with other rocks falling on top, thus creating tunnels and caverns and changing the depth of the fissure. The big difference between Silfra and other fissure is that when it cracked open the land, it cut into an underground spring filled with glacial meltwater coming from Langjökull glacier.