Ever since Earth was formed more than 4.5 billion years ago, the planet has been continuously shaped by dynamic forces.The most significant impact was made by the introduction of life.From the smallest single-cell organism to the most populous cities, living things--especially human beings--have had a profound effect on the planet.As a new millennium begins, conservation efforts are more important than ever for Earth's survival.Authoritative text and dramatic photographs show how our role in shaping the Earth can be just as significant as the massive eruptions of volcanoes or the shifting of huge tectonic plates.GLOSSARY, INDEX.
