Earth

Last evening on Prime I watched the first part of a BBC documentary Earth. This one was called Volcanos. I’m relying on memory so if my figures are wrong forgive me. Apparently about four billion years ago the Earth began to form when large rocks collided. The heat generated by these collisions became the molten core of the planet upon which the present tectonic plates float.

The programme began with striking shots of a rift valley in Iceland. I knew about the one in Africa but I hadn’t heard about this one. It continues under the Atlantic Ocean and represent the American plate shifting away from the European and African plates. The camera then shifted to our Southern Alps. From space they form a straight line.

As the plates shift they force up mountain ranges, Andes, Rockies, Alps and Himalayas. Earthquakes occur, shots of the last big one in north Pakistan. Water erodes these mountains even as they are pushed upright. Graphic shots from space of the silt-stained sea at the mouth of the Amazon.

The next scenes were thermal activity in Iceland and Rotorua. In hot pools like the one at Waiatapu life was formed by minerals and gases combining. Or maybe it was at sea in the areas where there is thermal activity there. These early life forms were very primitive.

A scientist in Namibia explained drop stones in alluvial rock, carried there by glaciers in an ice age which blanketed the earth about 700 million years ago. Like Mars and the opposite of Venus. Apparently this ice-age was ended by volcanic activity, the release of carbon dioxide into the atmosphere warming the temperature of the planet, a global warming.

Why the ice age and why the sudden spurt of volcanic activity was not explained. This after all was science.

The warming led to an explosion of life. This enabled shots of animals in all shapes and sizes, a kaleidoscope of great variety.

The programme finished with the self-regulating nature of the whole process, the carbon cycle. As life died the carbon dioxide was often returned to the soil and in time rock. Plankton especially – the tiny skeletons in their millions settled into the sediment and in time hardened into rock. In time as the plates shifted and one rode over the other the bottom one merged back into the molten core. There its carbon dioxide was released and some of the gas emerged with volcanic activity.

It was a fascinating and very satisfactory watch.

I got into the internet to check the last part of the programme. This information is from an anti-global warming site. I don’t know how suspect it is but it supports the argument. Apparently about 186 billion tons of carbon dioxide enters the earth’s atmosphere each year. Approximately 90 billion tons of that are from volvanic activity and decaying land plants. The piece said 'the earth’s oceans are the retirement home for most terrestrial carbon dioxide'.