Set inside Ţingvellir National Park, Almannagjá is a seven-kilometer-long fissure that illustrates the dramatic forces at work causing the drifting apart of the North American and Eurasian tectonic plates, which move away from each other by 1mm to 18mm a year. The only two places on earth where the effects of the separation two major continental plates can be observed are Ţingvellir and the Great Rift Valley of Eastern Africa.