Our planet Earth is in a constant state of change. Deep within our oceans, volcanoes erupt and tectonic plates shift. On land, rain and wind bring erosion and a constantly evolving character to our mountains and valleys. In our skies, the dynamic forces of weather bring change to all parts of the globe. Together, all these elements of earth, water, fire, and air combine to create an endless interactive cycle that has awesome power. The Our Living Planet series takes a detailed look at Earth's major natural environments and forces as it presents the important issues that surround each topic. A final section in each book provides a handson activity designed to further understanding of the subjects at hand.