Water covers more than 70 percent of Earth’s surface, and all of it is connected in the never-ending water cycle. A substance that can cut through solid rock, destroy cities, sculpt mountains and coastlines, and affect climate, water is a mighty force in nature. The power of moving water, such as in rivers, changes Earth’s landscape, creating valleys and deep canyons over time.
The Earth is made of layers, each with its own unique characteristics and processes that make it a vital part of the planet. The solid inner core, for example, is the farthest layer from the planet's surface, yet it provides much of the heat needed to fuel dramatic surface phenomena . Likewise, the outer core generates a magnetic field that protects the planet from harmful particles in space. In "Layers of the Earth", learn how scientists use modern tools land global positioning systems to study the workings of the inner Earth.
Year 501, the Conquest Continues
Secrets, Lies and Democracy
The Prosperous Few and the Restless Many
What Uncle Sam Really Wants
The Prosperous Few and the Restless Many
How many times have you heard it's important to get a good night's
sleep? It sounds simple, but it isn't always easy. Now one of the
nation's leading sleep experts gives you a step-by-step program for
overcoming sleep problems from insomnia and snoring to restless legs
syndrome and sleep apnea.
Dr. Lawrence Epstein of Harvard Medical School reveals his proven
six-step plan to maximize your nights and energize your days. He
explains the health benefits of sleep and identifies signs of sleep
problems as he gives in-depth advice on how to:
Turn your bedroom into the optimal sleep environment
Finally overcome insomnia
Silence buzz-saw snoring
Relax restless legs
Deal with daytime exhaustion
Determine if sleep medication is right for you
Improve your sleep by improving your child's sleep
