Formed by rapidly erupting lava 31-million years ago, the Semien Mountains in northern Ethiopia, near Gondar in Amhara region, look like a map of Middle Earth. The highest part of the Ethiopian Highlands, the mountains are surrounded by a steep, ragged escarpment with dramatic vertical cliffs, pinnacles, and rock spires – scenery that draws international tourists. The basalt volcanic rock that forms the range, a Unesco World Heritage Site, is up to 3,000 meters thick.