How the Rock Cycle Works (Electronic book text, annotated edition)

Glaciers are enormous masses of ice that slowly move across the Earth's surface. But how does something so big move on its own? And why are people concerned that glaciers might be melting more quickly? The answers to these probing questions and more can be found in this fascinating eBook. The eBook includes dazzling photographs of these icy behemoths as well as graphic organizers and annotated illustrations to aid learning.