See the awesome destructive power of landslides.

Tsunamis are giant, powerful waves most often caused by earthquakes beneath the ocean floor. Their incredible power can destroy entire communities, then drag the debris out to sea. This video shows what causes tsunamis and the importance of evacuating any area under a tsunami alert.

The Secret Labbers learn about gemstones from Sheila. She also gives examples of the real-world applications of minerals, such as diamonds. Watch Thomas Edison's Secret Lab on Netflix, the Kid Genius channel on Xfinity, public television and DVD. Visit EDISONSECRETLAB.COM for games, videos, downloads and more!

Beakman explains how caves are formed by acid dissolving limestone and he uses a model to show how this happens. He explains there are two major sections of a cave called the twilight zone (little light reaches in) and the dark zone (no light reaches). Beakman describes the different animals that live there and their features. They also talk about stalagmites and stalagtites and then make their own.

Sabrina illustrates the different types of landforms that exist and explains how each of them is created. The landforms she covers are: mountains, valleys, plateaus, deserts, islands, and deltas. She explains that landforms are one of the ways that nature has shaped the Earth.