Gribbin - Planet eartha beginners guide

aesthetics

africa

anarchism

aquinas

art

artificial intelligence

the bahai faith

the beat generation

biodiversity

bioterror & biowarfare

the brain

british politics

the buddha

cancer

censorship

christianity

civil liberties

classical music

climate change

cloning

cold war

conservation

crimes against humanity

criminal psychology

critical thinking

daoism

democracy

descartes

dyslexia

energy

engineering

the enlightenment

epistemology

evolution

evolutionary psychology

existentialism

fair trade

feminism

forensic science

french revolution

genetics

global terrorism

hinduism

history of science

humanism

islamic philosophy

journalism

judaism

lacan

life in the universe

literary theory

machiavelli

mafia & organized crime

magic

marx

medieval philosophy

middle east

NATO

nietzsche

the northern ireland conflict

oil

opera

the palestineisraeli conflict

paul

philosophy of mind

philosophy of religion

philosophy of science

planet earth

postmodernism

psychology

quantum physics

the quran

racism

renaissance art

shakespeare

the small arms trade

the torah

sufism

volcanoes

A Oneworld Paperback Original

Published by Oneworld Publications 2012
This ebook edition published 2012

Copyright John and Mary Gribbin 2012

The moral right of John and Mary Gribbin to be identified as the Authors of this work has been asserted by them in accordance with the Copyright, Designs and Patents Act 1988

All rights reserved
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from the British Library

ISBN 978-1-85168-828-9
Ebook ISBN 978-1-78074-042-3

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We live on a planet. Our home is a nearly spherical ball of rock, about 12,700 kilometres (7900 miles) in diameter, covered with a thin smear of water and gas, orbiting around the star we call the sun once every year. As it orbits, the Earth turns on its axis, at present once every twenty-four hours, giving us the cycle of day and night. This has been going on for, in round numbers, 4.5 billion (thousand million) years, the time since the sun and its family of planets formed. That is the extent of the history of terrestrial time, the framework within which the present features of the Earth, including its suitability as a home for life, have evolved.

We cannot tell that whole story here. But we will tell you how the forces that shaped the Earth are still active today, causing earthquakes and volcanoes, ripping the Earths crust apart as ocean basins grow, and pushing landmasses around in a changing pattern that produces collisions between continents in which great mountain ranges grow. Both geological activity and life combine to influence the composition of the air that we breathe, and life itself both responds to changes in the climate of our planet and drives some of those changes, including the present warming of the globe.

The story of our home planet as it is today is not just of interest to Earth scientists, but is of compelling importance to everyone alive on Earth today, at the mercy of inexorable geological forces. Now, lets take our journey.

Before we begin the story of our home planet, we should first consider another story of terrestrial time, the story of how pioneering geologists came to realize the true extent of the history of the Earth, and the nature of the forces that have shaped, and continue to shape, the world we live in. That history goes back scarcely more than two hundred years, to the time when scientists in Europe first began seriously to question the idea, derived from a literal interpretation of biblical stories, that the Earth is only some six thousand years old.

The birth of geology

The modern understanding of the Earth began with the work of the Scotsman James Hutton, who had qualified as a physician, but was wealthy enough never to have to work and devoted his life to science. He presented his ideas to the Royal Society of Edinburgh in 1785, and published them in a book, Theory of the Earth, in 1795. The Geological Society of London, the first organization devoted to the study of what are now called the Earth sciences, was founded just twelve years later, in 1807. By then, Huttons pioneering ideas had been popularized by his friend John Playfair in his book Illustrations of the Huttonian Theory of the Earth.

At the end of the eighteenth century, although it was still widely believed that the Earth had been created in 4004 BC , scientists like Hutton were well aware that our plant must be much older than this. The question was, how old? And how had the landscape been shaped into its present form?

The puzzle had been hinted at as far back as 1665, by Robert Hooke, in his book Micrographia. Hooke was one of the founding fathers of science, but doesnt always get the credit he deserves because he was a contemporary of Isaac Newton, compared with whom even the cleverest people look ordinary. Hooke was one of the first people to realize that fossils arent just curiously shaped rocks that happen to resemble living things, but are the preserved remains of living things themselves. Describing ammonites in his book, he wrote that they are the Shells of certain Shelfishes, which, either by some Deluge, Inundation, Earthquake, or some such other means, came to be thrown to that place, and there to be filled with some kind of mud or clay, or