Mount Edziza Volcanic Complex
The
distribution of volcanoes on the planets is not uniform.
Volcanoes are known on the Earth, Mars, Venus, and
several moons of the planets. On Earth, volcanoes
are associated with converging and diverging plate
margins. Even on these margins however, there are
large volcanic complexes that represent the locus
of repeated volcanic activity. Iceland, for example,
is a large volcanic file on the Midatlantic Ridge.
Volcanic complexes occur in plate interiors, for
example Hawaii in the middle of the Pacific plate
and the Craters of the Moon - Snake River Plain basalt
field in the middle of the North American plate.
A smaller volcanic complex, the Mount Edziza Volcanic
Complex (Souther, 1992) in northern British Columbia
is one of several large volcanic complexes in western
Canada. A myriad of volcanic features make up the
complex. Basaltic shields, composite volcanoes, rhyolite
domes, caldera complexes, and pyroclastic rock bodies
are all found in the Mount Edziza Complex. The ages
of the volcanic rocks span at least the last 7.5
Ma. The youngest date obtained, 1340 years BP, was
obtained from twigs in the soil beneath one of the
youngest cinder cones.
This photograph was taken from a young cinder cone on
the northwest slope of the Complex. The cinder cone,
Eve Cone, that you see in the photograph is one of
the youngest features in the Mount Edziza Complex.
What controls the distribution of volcanoes on the planet?
Is the number of factors that control the distribution
so large that the distribution appears to be random?
If the past distribution volcanoes was known, could
we predict the future distribution?
How long will volcanic activity last on earth? Both
Mars and the Moon are likely dead bodies with respect
to volcanic activity.
jim.nicholls@shaw.ca
