Earth Science

Topics: Plate tectonics, Earth, Geology Pages: 3 (888 words) Published: March 21, 2013
1. Summarize advances over time in determining the age of the Earth, including the importance of the discovery or radioactivity. Herodotus counted layers of earth near the Nile River in 450 B.C.E. The Bible was used in the Middle Ages to compute the age of the Earth. The 18th and 19th centuries brought a more scientific look into determining the age of the Earth by studying the salinities of the oceans, the rates of sedimentation, and models of cooling of different materials in order to calculate the Earth’s age. In 1862, William Thompson calculated the Earth’s age to be 98 million years and recounted that age to determine that it was actually between 20 and 40 million years old. He used a very thorough method and ended up being wrong on both counts because he was unaware of the existence and effects of radiation. There was another method of aging the Earth utilizing the relative positions of rock layers. Ensuring that unconformities were accounted for, that fossils were used as benchmarks, and understanding what rocks are older than others, this relative aging helped to develop a geologic time scale. The discovery of radioactivity allowed scientists to understand heat better. The radioactive decay of elements helps scientists calculate the age of an object by using the statistics of large numbers. 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. At the time of the Big Bang, an unimaginable cataclysm released helium and hydrogen. Soon after the Big Bang, energy began converting into matter. Large clouds of this matter began attracting to other particles which formed everything, including our Solar Systems. The beginning of the Solar System started with a cloud of gas, dust, and ice particles. Gravity acted on the cloud, drawing it into itself and reducing its volume. This occurrence would have caused the...
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