Geology Reference
In-Depth Information
gist, it is conceivable that plate tectonics could not happen without the calcium carbon-
ate laid down by living beings at the edges of subduction zones, for the great weight of
these sediments could be softening the underlying rocks, making them pliable enough to
plunge into the deep Earth.
Volcanoes, hot springs and earthquakes are perhaps the most obvious manifestations
of tectonic activity, but there are more unusual ways of encountering the immense
churning energies deep beneath the crust of the Earth that keep her plates in constant
motion. Once, as a member of a zoological expedition to the Caribbean island of Domin-
ica, I hiked with a friend up to Trafalgar Falls, deep within the balmy forest. We
clambered around many huge boulders that lay strewn along the lower reaches of the
valley and, happily suffused with the blessings of the ample green forest and the tropical
sunshine, we reached the peaceful solitude of the falls. The cascades were inviting, and
as we bathed and wallowed beneath the luscious curtains of crystalline water we dis-
covered a narrow geothermal torrent gushing hot water like none I had ever encountered.
It was as if the experiences of its long journeys through the dark hot rocks far from the
realms of air and light, of its long contact with semi-molten basalt and newly formed
granite, permeated my skin like richly scented oil. This was a warmth charged with an
unexpected communicative power. The cascading water informed my sensing body of
the rocky underworld that lay beneath our feet, far below the threshold of our everyday
awareness; a realm, in its own way, as animate and turbulent as the wind, rain and ocean
of our daylight world.
This geothermal energy is vitally important, for Gaia would freeze without the return
of carbon dioxide from the fusing and melting of calcium carbonate and silica beneath
her moving rocky plates. But what if too much carbon dioxide returns to the atmosphere
through volcanoes— wouldn't Gaia be seared to death by temperatures far too high for
life to bear? This is indeed a mortal danger, but as we have seen, Gaia has remained
wonderfully poised within habitable temperatures over much of her long life. How is
this possible? It seems that the slow
tai chi
dance of negative feedback has kept the tem-
perature right for life, a great dance that involves all the living beings, rocks and gases
we have encountered so far, the dance of carbon's great chalk journey through Gaia.
