STEM Magnetic stripes and isotopic clocks [This Dynamic Earth, USGS] Oceanographic exploration in the 1950s led to a much better understanding of the ocean floor. Among the new findings was the discovery of zebra stripe-like magnetic patterns for the rocks of the ocean floor. These patterns were unlike any seen for continental rocks. Obviously, the ocean floor had a story to tell, but what? In 1962, scientists of the U.S. An observed magnetic profile (blue) for the ocean floor across the East Pacific Rise is matched quite well by a calculated profile (red) based on the Earth's magnetic reversals for the past 4 million years and an assumed constant rate of movement of ocean floor away from a hypothetical spreading center (bottom). A team of U.S. Other commonly used isotopic clocks are based on radioactive decay of certain isotopes of the elements uranium, thorium, strontium, and rubidium. "Developing the theory"
Technology Strategies NASA Earth Observatory : Home Music Physical Science Earth Science A WebQuest about WebQuests Introduction Since early in 1995, teachers everywhere have learned how to use the web well by adopting the WebQuest format to create inquiry-oriented lessons. But what exactly is a WebQuest? The Task To develop great WebQuests, you need to develop a thorough understanding of the different possibilities open to you as you create web-based lessons. By the end of this lesson, you and your group will answer these questions: Which two of example WebQuests listed below are the best ones? The Process First, each participant will have a hard copy of the worksheet. Conclusion Ideally, this exercise will provide you with a larger pool of ideas to work with as you develop your WebQuest-making skills.
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