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[Winds, Fronts, and Cyclones] Warm air rises above cold air at a front. This is because warm air is less dense than cold air. Along a warm front, warm air advances over a retreating cold air mass. Select the image below that represents a warm front.

[Volcanic Hazards] Based on what you know about viscosity and composition, rank the magma compositions from least explosive to most explosive. Hint: Explosivity occurs when gases are unable to escape from a thick magma, causing pressure to build up.

[Volcanic Hazards] Temperature influences the viscosity of many materials. Would you expect a high-temperature magma to be more or less viscous than a lower temperature magma?  

[Volcanic Hazards] Match each term below to the appropriate image.

 [Minerals] Cleavage and hardness are two separate characteristics of a mineral. Take diamonds, for example. The tag line is that “diamonds are forever.” This is true if you think only about scratching. Diamonds are very scratch-resistant, so they have a high hardness rating on Mohs scale for hardness. If you take a hammer to a diamond, you will see that it fractures as easily as many other minerals. Odds are you will upset someone as well. Below are two minerals. Use Mohs scale for hardness to determine which mineral is harder. Click on the harder mineral.

[From Big Bang to Blue Marble] A geologist discovers a solid material with an unordered atomic arrangement that formed from rapid cooling of molten rock. Which material classification is most accurate?

[Plate Tectonics] On the following map, there are six boxes at different plate boundaries. Using the arrows showing relative plate motion, label each box as a convergent or divergent plate boundary.

[Plate Tectonics] Plate motion leads to the building of mountains and the occurrence of large earthquakes every year. How far will an average plate move over the course of a year?

[Winds, Fronts, and Cyclones] Where two air masses meet, a front is formed. In the animation below, click on the “Topics” menu and select the “Frontal Lifting” segment to learn about the process of frontal lifting. What type of front is shown in the animation? Hint: Does the temperature at the Earth’s surface get warmer or colder? Click here to open the animation in a new window.  

[Volcanic Hazards] In the animation below, watch the Introduction. Then click on Topics, and select Partial Melting. You will see what a rock looks like through a microscope. The individual crystals are different materials. Set the green bar on the left to 800°F (just above low temperature). Then, click the Migrate Magma button. Use the information you gather to answer the next five questions. Lava Composition What is the composition of the melt that has been mobilized?