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Volcanoes of the Galapagos Islands
 The
Galapagos Islands
are very young in geologic terms, Española the oldest of the islands
was formed 3 to 5 million years ago from a volcanic hot spot located on
the sea floor. The hot spot is an area where the magma is so hot it
burns through the earth's crust and the magma below is allowed to reach
the crusts surface forming a volcano. As the hot spot discharges
materials it begins accumulating, spreading and rising. The discharged
materials reach a level of 6,000 to 10,000 ft (2,000 to 3,000 m) from
the ocean floor. As the Plate at the ocean floor moves at a rate of 3
inches per year (5 cm) the volcano breaks free of the stationary hot
spot forming an independent island. As the hot spot continues to emit
material a new island is born using this process. As new islands are
formed and the plate continues to move a chain of islands is formed.
The Galapagos hot spot is located to the east of Fernandina,
the youngest of the islands at approximately 1 million years of age. A study
of geology in action, the Galapagos Islands is one of the world’s most
active volcanic areas, with more than 50 eruptions in the past 200 years.
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Six of the volcanoes are still active (1 on Fernandina
and 5 on Isabela). The most recent explosion was Cerro Azul on
Isabela in
September of 1998. The type of volcanic make up characterizes the island's
look. Most of the Galapagos Islands were made from a single volcanic cone
creating a high point of the island with gentle slopes and a flat coastline.
Española (the oldest of the chain) and Fernandina (the youngest in the
chain) with their single volcanic cone are typical of most of the islands
known as a shield volcano.
Shield volcanoes are formed from a build of fluid lava
flows. As the flow emits from the central vent it pours out in all
directions creating a broad, gently sloping cone of flat, domical shape. The
profile is said to resemble a warrior's shield giving these volcanoes their
name. The volcanoes build up slowly the result of thousands of fluid basalt
lava flows. |
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 The lava cools into thin layers, which continues to accumulate for years,
eventually giving the volcano its height. Shield volcanoes make up some of the
largest volcanoes in the world including Mauna Loa in Hawaii, which rises 28,000
feet above the ocean floor. Isabela the largest island of the Galapagos
Archipelago was created from the fusion of 6 shield volcanoes. Volcanic Plateaus formed South Plaza, Baltra, and Seymour
Islands. Plateaus create when the eruption of basalt lava poured quickly from
fissures rather than central vents. The lava surrounds the area and with lava
flow upon lava flow, forming broad plateaus. Lava plateaus of this type are
located along the Snake River in Idaho, and the Columbia River in Washington and
Oregon. Those lava flows are exposed and measure more than a mile in total
thickness.
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