Bill goes to the depths of the Earth (literally) to explain how the Earth's surface and its inner mantle differ.

Features: fully indexed "chapters" correlated to National Science Standards; interactive glossaries and quizzes; bonus footage of never-before-seen segments, interviews, and demos; on-disk implementation guide. Features: fully indexed "chapters" correlated to National Science Standards; interactive glossaries and quizzes; bonus footage of never-before-seen segments, interviews, and demos; on-disk implementation guide.