Earth Case

1.Summarize advances over time in determining the age of the Earth, including the importance of the discovery or radioactivity.

There were several advances that helped with determine the age of the Earth. Some of these advances included as far back as 450 B.C.E.. Herodotus, who had Egyptians dig trenches along the Nile River because the Nile deposits a layer of sediment every year. He went in and counted the layers and was able to identify 5,000 layers. Therefore, he concluded that the earth was at least 5,000 years old. In the Middle Ages, people used sacred texts, such as the Bible, to calculate the age of the Earth. One of the most famous people of the Middle Ages is Irish Bishop Usher, who used the Old Testament to calculate the age of the Earth. He determined that the earth was formed on October 23, 4004 B.C.E, at 9:00 a.m.. In the 18th and 19th centuries, people used a variety of techniques. These techniques include looking at salinities of the ocean, the rates of sedimentation, and models of the cooling of different materials in order to try to figure out how the earth was. Radioactivity plays a major role in determining the age of the Earth. Radioactivity provides the heat that keeps our planet going. We owe our very existence to the radioactivity decay of three elements, uranium, thorium, and potassium. If it were not for the radioactivity of these three elements, we would not exist and life would not be here. Our planet would be a dead cinder floating in space. There would no oceans, no atmosphere, no plate tectonics, and no continents.

2.What makes Earth a habitable, relatively stable environment within which we exist and survive? Review the early development of the solar system, including the Big Bang theory, to support your answer.

Earth is habitable, relatively stable environment within which we exist and survive is due to the Earth's location within the solar system.

3.Alfred Wegener was a polar explorer and visionary. Describe how his early work was viewed with skepticism and how ultimately his theory on continental drift was proven. What kinds of evidence did Wegener rely on to substantiate his continental drift hypotheses (Pangaea)?

4.Explain how seismic tomography has been used to show what is actually happening on Earth. Include in your answer a discussion of plate tectonics and sea-floor spreading. Explain how the laws of thermodynamics determine the motions that result in the formation of mountains and oceans.

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