The island of Santiago is located near the center of the Galapagos Islands, off the coast of Ecuador. The Galapagos Islands are situated near the equator, and were formed from volcanism related to a large mantle plume. This hot spot is very close to the tectonic boundary between the Galapagos Ridge and the Nazca and Cocos plates. This combination of mantle plumes and tectonic plate movements produces a unique geological environment, including underwater ridges of volcanoes that influence the water circulation around the Galapagos. Santiago itself was formed from a shield volcano. Several dark lava flow fields are visible in this astronaut photograph, the largest along the eastern, western, and southern coastlines. The small Isla R獺bida to the south is the peak of another, mostly submerged shield volcano. At image center is a large but isolated region of green vegetation on the south-facing slope, below the summit ridge. This image was taken during the dry, or gar繳a, season that lasts from June to November.