Like many oceanic islands such as Hawaii, the Azores, and Reunion, the Galapagos are thought to be the product of a mantle plume. Mantle plumes are columns of hot rock, roughly 100 km in diameter, that rise from deep within the earth. These plumes rise because they are hotter (by perhaps as much as 200 degrees centigrade) and therefore less dense than the surrounding rock. The rate of ascent is about 10 cm/year or so.

Hence, the islands are the tips of volcanic cones, some still active. Actually, the Galapagos is one of the regions with the greatest volcanic activity in the world registering 55 major eruptions as of late - the latest in Marchena in 1991 and Fernandina in 1995.

There are two types of volcanoes in the Galapagos Islands. In the west, on the islands of Isabela and Fernandina, large volcanoes with an upside-down soup bowl or deep calderas occur. In the east, smaller shield volcanos with gentler slopes occur. The difference between these two volcanoes is the difference in lithospheric thickness. The the upside-down bowl is not common, and scientists are uncertain of its origin.

WThe highest point of the islands is located on Isabela Island. Wolf Volcano reaches 1,707 meters high and 2,000 fathoms (1,852 meters) deep. Because of the islands' vivid history, many have two or even three names. Most maps, including the map we provide, list them all.