February 13, 2007 • 50m
Why is the Earth so restless? What causes the ground to shake violently, volcanoes to explode, and great mountain ranges to rise t...Read more
February 16, 2007 • 50m
Beautiful, bewildering, and bizarre - our oceans dominate our planet. How did they form? Why haven't they evaporated? Starting wit...Read more
February 21, 2007 • 50m
Why do mountains have a triangular shape? How much rain must fall to start a river? How does one grain of sand become an entire du...Read more