Þingvellir (Pronounced Thingvellir) is a UNESCO World Heritage Site and is the meeting place of the european and north american tectonic plates which is one reason that Iceland is so geologically active. I believe this particular waterfall is in the canyon called Almannagjá which is the actual divide between the plates, so the water is coming over the American plate and crashing down on the European one (but don't quote me on that!).
