Fossil Evidence that
illustrates how life forms
evolve
Techniques used to
determine geological time
scales
techniques used to learn
about the earth
Impact of Earthquakes
on the Enviroment
Factors responsible for
Earthquakes
Factors responsible for
mountain building
Factors Responsible for
Ocean Ridges
Factors Responsible for
Volcanic Eruptions
Theory of Plate
Tectonics
Impact of Volcanoes
on The Enviroment
Bibliography
Formation of Ocean Ridges
About 80 percent of all volcanic activity occurs at the mid-ocean ridges.
Ocean crust is formed at mid-ocean ridges and oceanic volcanoes by a
series of melting and cooling events. These leave a geochemical imprint
in the making of the crustal rocks. Volcanic eruptions are caused by the
molten magma that wells up inside the earth. In some cases submarine
volcanic activity produces chains of volcanoes. Eruptions and the internal
movements of magma in active oceanic volcanoes trigger earthquakes
and landslides, which reshape the volcanoes.
The mid-oceanic ridges rise 3000 meters from the ocean floor and are
more than 2000 kilometers wide. Mapping of the seafloor reveals that
huge underwater mountain ranges have a deep trench that bisects the
length of the ridges and in places is more than 2000 meters deep. The
greatest heat flow was centered at the crests of these mid-oceanic ridges.
The mid-oceanic ridges experience a large number of earthquakes.
