Volcanoes
The Galápagos Island region is one of the most volcanically active areas
in the world. The first islands were formed between three and five million
years ago, when underwater mountains formed by successive volcanic eruptions
began to emerge from the sea. Island formation following the same process
has continued ever since. Since 1535, when the islands were discovered, over
50 eruptions have been recorded, the most recent of which just occurred on
Fernandina in May 2005.
Geologists use the theory of plate tectonics and the hotspot theory to
explain the formation and evolution of the Galápagos Islands . According to
the theory of plate tectonics, the earth's outer crust is comprised of a
series of dynamic terrestrial pieces, or plates, which move with respect to
one another in one of three patterns: they can spread apart, slide past, or
collide with one another. Near the Galápagos, tectonic activity follows an
interesting yet complicated pattern influenced by the convergence of three
plates—the Pacific, the Nazca, and the Cocos Plates. The island archipelago
is located on the northern boundary of the Nazca Plate near its junction
with the Cocos Plate, but it is not at rest there. Sea-floor spreading along
the Galápagos Rift causes the islands to move south and east at the rate of
7cm/year.
The hotspot theory says that certain stationary points within the mantle,
the earth's middle layer, have the unique capability of periodically
superheating. When the heat from these areas increases enough to melt the
crust, a volcanic eruption will result with enough strength to drive molten
lava above the ocean's surface. As tectonic plates move across the fixed hot
spot, a trail of volcanoes will follow, each aging and eroding with time.
Since the Galápagos are moving southeast over the hot spot, geologists have
determined that the oldest islands must be San Cristóbal and Española, in
the southeast archipelago, and the newest islands must be the northwestern
islands of Fernandina and Isabela. In fact, these islands, which are
situated directly over the hot spot, are still in the process of formation.
Most of the volcanic rocks and magma forming the eruptions in the
Galápagos are basaltic, characterized by their low levels of silicon and
oxygen and subsequently slow rate of flow. Since eruptions thus take the
form of gradual flows instead of explosions, the volcanoes that develop tend
to have smooth, shield-shaped outlines and rounded tops instead of the more
well-recognized cone-shape. As the lava flows, its surface layer comes into
contact with the air, cools, and slows down, resulting in the formation of a
crust with a distinctive superficial appearance: pahoehoe (braided), aa
(jagged), or schrict (ropy). These lava formations are commonly seen at
Sullivan Bay on the eastern side of Santiago.
The wildlife you will see on your Galapagos tour are completely
unaffected by Galapagos travel visitors . For this reason, there is a
restricted number of visitors permitted into the Galapagos each year, as
part of a joint effort to protect the delicate environmental and
ecological equilibrium. The most sensible method of Galapagos travel is
via our cruise ships. The M/V Galapagos Legend provides 3 night, 4 night
and 7 night cruises to select from, which can also be easily merged with
Galapagos travel visits to neighboring South American locations