Sunday, February 12, 2012

Sitting on top of a volcano

Steam vents at the Craters of the Moon, Taupo
Here in New Zealand we are perched on a land mass where two continental plates collide. Below us, the friction and fracturing create tremendous heat and release the molten rock that lies beneath the crust.

When that magma contacts groundwater, the steam finds its way up to the surface in the form of vents and geysers and bubbling hot springs. They make up one of the tourist attractions around the two big islands. The Earth here shudders and moves. A year ago, hundreds of people were killed in Christchurch on the South Island when a major earthquake struck.

Craters of the Moon, Taupo
 Yesterday, Cindy and I hiked around the south part of the lake here in Rotorua, and sulfurous hot water came bubbling up along the shore and out in the lake. It smells like rotten eggs. The ducks and geese don't seem to mind. 

The unstable Earth

All of this heat and bubbling and shaking are just a reminder of how unstable the Earth is. We tend to think of our planet as something solid and unchanging. But since long before man appeared, it has been in a constant state of flux, with ice sheets descending from the poles and then receding, sea levels rising and falling, land masses migrating thousands of miles, mass extinctions of species and massive climate changes. The magnetic poles of the earth have flip-flopped dozens of times. In other words True North is a temporary thing.

You need look no further here than the limestone visible in the mountains. It was formed from sea floor deposits and is filled with shells of tiny marine animals. How did creatures from the sea floor end up in rock several thousand feet above sea level? The planet is in flux.

Historical geology with jokes

The writer Bill Bryson is known mainly for his humor, but he did a fascinating book about the origins of our planet, A Short History of Nearly Everything. It is an easy read in spite of its being about a subject guaranteed to intimidate those with science phobia, namely historical geology.

Bryson lingers for many pages on the geology of Yellowstone National Park, described as a thin layer of rock barely containing a molten caldron of magma that may explode at any time with many times more force than atomic weapons. It makes our human conflicts and technologies seem very small indeed.

Redwood Forest, Rotorua
As if we weren't already feeling small, we took a hike through the Redwood Forest in Rotorua. Even though these trees are not much more than 100 years old, they are massive. They represent one of the many species of plants and animals introduced into the New Zealand ecosystem, which had been isolated from the influence of man until about 800 years ago. 

New Zealand's forests have been stripped and restored a number of times, first by the Maori, then by the Europeans, now by industrialized harvesting. Still, New Zealand's government has created many reserves, parks and protected areas. The words that come to mind are green and clean. 

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