 Complete the following phrase:  The Galápagos Islands are an isolated set of volcanoes, consisting of shield volcanoes and lava plateaus, about west of Ecuador. They are driven by the Galápagos hotspot, and are between approximately 4.2 million and 700,000 years of age. The largest island, Isabela, consists of six coalesced shield volcanoes, each delineated by a large summit caldera. Española, the oldest island, and Ferdina, the youngest, are also shield volcanoes, as are most of the other islands in the chain. The Galápagos Islands are perched on a large lava plateau known as the Galápagos Platform. This platform creates a shallow water depth of at the base of the islands, which stretch over a diameter. Since Charles Darwins visit to the islands in 1835 during the 