7.2: Geologic Time
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It was pointed out in the previous section that the earth is approximately 4.5 billion years old. The magnitude of geologic time is of great importance to our understanding of earth processes that we have discussed in this class. Last week when we discussed weather and climate, it was pointed out that ‘weather’ refers to a short term event – on the order of a few days, while ‘climate’ describes trends in weather over decades. Thus, the concept of ‘climate change’ becomes greatly altered when we consider the length of earth history. We humans often try to put everything in the perspective of a person’s lifetime (perhaps a century). However, most earth processes operate on the scale of a millennium (1000 years) or more. The history of the earth is vast, and its appearances and processes have developed over a time scale which is significantly greater than ours.
Read over William Newman’s discussion of Geologic Time, focusing on Geologic Time, The Relative Time Scale, and the Age of the Earth.
Contributors and Attributions
K. Allison Lenkeit-Meezan (Foothill College)