Sangay (also known as Macas, Sanagay, or Sangai) is an active stratovolcano in central Ecuador. It exhibits mostly strombolian activity. Geologically, Sangay marks the southern boundary of the Northern Volcanic Zone, and its position straddling two major pieces of crust accounts for its high level of activity. Sangay's approximately 500,000-year-old history is one of instability; two previous versions of the mountain were destroyed in massive flank collapses, evidence of which still litters its surroundings today. Due to its remoteness, Sangay hosts a significant biological community with fauna such as the mountain tapir, giant otter, Andean cock-of-the-rock and king vulture. Since 1983, its ecological community has been protected as part of the Sangay National Park. Although climbing the mountain is hampered by its remoteness, poor weather conditions, river flooding, and the danger of falling ejecta, the volcano is regularly climbed, a feat first achieved by Robert T. Moore in 1929. Geological setting Lying at the eastern edge of the Andean cordillera, Sangay was formed by volcanic processes associated with the subduction of the Nazca Plate under the South American Plate at the Peru–Chile Trench. It is the southernmost volcano in the Northern Volcanic Zone, a subgroup of Andean volcanoes whose northern limit is Nevado del Ruiz in Colombia. The next active volcano in the chain, Sabancaya, is in Peru, to the south. Sangay is above a seismogenic tectonic slab about beneath Sabancaya, reflecting a sharp difference in the thermal character of the subducted oceanic crust, between older rock beneath southern Ecuador and Peru (dated more than 32 million years old), and younger rock under northern Ecuador and Colombia (dated less than 22 million years old). The older southern rock is more thermally stable than the northern rock, and to this is attributed the long break in volcanic activity in the Andes; Sangay occupies a position at the boundary between these two bodies, accounting for its high level of activity. Legend Many say that gold lies under Sangay. Geology Sangay developed in three distinct phases. Its oldest edifice, formed between 500,000 and 250,000 years ago, is evidenced today by a wide scattering of material opening to the east, defined by a crest about high, pockmarked by secondary ridges; it is thought to have been in diameter, with a summit southeast of the present summit. The curved shape of the remnants of this first structure shows that it suffered a massive flank collapse,