Galapagos islands are located in one of the most active oceanic
volcanic regions on earth, It is located on the Nazca Plate, close
to its junction with the Pacific and Cocos Plate. The islands
are moving south and eastward at a rate of more than 7 cm/yr.,
which may not seem fast but would, over a million years , amount
to 70 km of movement!
Where a sea floor plate is moving toward a continental mass, the
sea floor plate is forced under the continent. This process is
called subduction, occurs on the west coast of South America where
the nazca plate is colliding with the American continent. There
are many earthquakes along the Coast because of this process ,
the building of the Andes and the presence of volcanoes .
The evidence that the plate on which the islands sit is moving
eastward is that the oldest islands are in the eastern part of
the archipelago. There is also volcanic activity where the western
island are now. In fact, it is on these Western Islands where
all the recent volcanic activity has occurred, while the Eastern
Islands are the oldest . The "Hot Spot Theory" states
that in certain places around the earth, there are more or less
stationary areas of intense heat in the mantle. These hot spots
cause the crust to melt in certain places and give rise to volcanoes.
The Galapagos and Hawaiian Islands have mild volcanic eruptions
where volcanic material comes out gently to form large lava flows
rather than explosions. The molten magma forming these eruptions
are made of basalt. The result of these type of formations gives
the greatest combination of tropical volcanic islands , where
you can see abundant marine life, as well as terrestrial fauna
and flora , all in one unique diverse eco-system.