Environmental Engineering Reference
In-Depth Information
Plate 1
(a) Craters, cones and associated lava flows (dark rocks) of
the Cima Volcanic Field, East Mojave Preserve, southern
California. Their eruptive history spans the Quaternary period. (b)
A rhyolitic lava flow, some 3 km long, emanates from one crater.
Photos: Ken Addison.
likely to occur? Volcano-seismic activity almost anywhere around the Pacific Rim and
in the eastern Mediterranean region offers several potential sites. One site worth watching
is in Yellowstone National Park in the western United States. Although best known for its
hot springs and geysers, the United States Geological Survey (USGS) co-sponsors the
new Yellowstone Volcano Observatory, monitoring increased ground swelling
(diapirism) and earthquake activity. Like several others worldwide, the Yellowstone
calderas cover 10
3-4
km
2
, and were produced by cataclysmic eruptions 2 million, 1.3
million and 600,000 years ago. A repeat could threaten the economic and political pre-
eminence of the United States and exchange rapid global cooling for the current warming
(Plate 1).
CONCLUSION
We occupy the land surface of a living Earth and contribute in a minor way to its rock
cycle, by using and discarding geological resources and interfering with the energy flows
and components of endogenetic processes. Landscapes around us are strongly influenced
by their geological foundations and, armed with sufficient knowledge and the right
techniques, we are able to reconstruct their palaeo-environmental history. Long time
scales should not deflect us from the need to understand our geological environment and
heritage. Large human populations living along plate boundaries are only too aware of
