A section of the mid-Atlantic Ridge where the African and South American Plates are created. A rift valley over a
mile (2 km) deep marks the axis of the ridge. Depths range from 1900 (pink) to 4200 meters (dark blue). Image used
with permission of Ken Macdonald.
Divergent (or spreading centers) plate boundaries are characterized by features called mid-ocean ridges. Combined,
the ridges are nearly 46,000 miles (74,000 km) long. The ridges are home to Earth's highest mountains, deepest
canyons, and longest escarpments. The shape of the mid-ocean ridge and the style and rate of volcanism is controlled
by the rate the plates move apart.
Growth of tectonic plates at mid-ocean ridges. This photo shows a ropy lava flow erupted in April 1991, on the floor
of the axial summit collapse trough of the East Pacific Rise near 9 degrees 50.6'N. Note dead tubeworms. Photography
courtesy of Woods Hole Oceanographic Institution and members of the Adventure dive
(Principle Investigators: D. Fornari, R. Haymon, K. Von Damm, M. Perfit, M. Lilley, and R. Lutz).
New oceanic plates are created at mid-ocean ridges. About 2.4 cubic miles (10 cubic km) of new oceanic crust is
added each year (not all of this magma is erupted by volcanoes). This is about 100 times the volume of lava erupted
by Kilauea each year.
As you might have noticed we are in the process of changing to a new style of website. This is a significant upgrade over all previous versions of VW and will allow this website to carry on for some time into the future without any further changes. We understand and apologize that things have been changing so often here, but each step has been required for us to keep the website going. This change will guarantee that VW is always up to date!
Most of the older content is still here!!
I suggest using the search box on the homepage first.
Growth of tectonic plates at mid-ocean ridges. This photo shows a ropy lava flow erupted in April 1991, on the floor
of the axial summit collapse trough of the East Pacific Rise near 9 degrees 50.6'N. Note dead tubeworms. Photography
courtesy of 