Geoscience Reference
In-Depth Information
of the world's volcanoes in
The Natural History
, but then it killed
him. We can be certain about volcanic extinctions such as those
in Edinburgh, where Arthur's Seat is a 350-million-year-old
volcanic plug, well worn by later glaciations, and no longer
plugging back any hot eruptive material. We can also be sure that
the volcanic activity that formed the Northwestern Hawaiian
islands, the tail of the chain of islands pointing northwest, ceased
more than seven million years ago. This is because the thinner
part of the lithosphere that created the 'hotspot', which allowed
them to be formed has moved away from them with the motion
of the Pacific plate, to enable the creation of Hawaii's Big Island.
By contrast, the hotspot from which Iceland emerged on the
mid-Atlantic ridge about 20 million years ago - long after the
extinction of the dinosaurs - is static in relation to the divergent
tectonic plates. For this reason the island remains actively volcanic.
A type of volcano that can only be imagined by artists is
the supervolcano. These lie, neither active, dormant nor extinct,
beneath the lithosphere in places including Yellowstone in the usa,
the Campi Phlegraei near Naples, Sumatra and New Zealand.
A relatively recent taste of their power was experienced in 1815
when Tambora erupted in the Philippines, and in 1883 when
Krakatoa erupted. Volcanologists today may be able with sophis-
ticated equipment to forecast volcanic activity and try to evacuate
local populations, but there is nothing that they or any human
beings can do to stop eruptions. We are living on the top of the
furnace that supports us, another of the exciting and unpredictable
aspects of being human.
