111-25 - GY 111 Lecture Notes D. Haywick (2008-09) 1 GY 111...

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GY 111 Lecture Notes D. Haywick (2008-09) 1 GY 111 Lecture Notes Geological Time Lecture Goals : A) How long is long? B) Geological time divisions C) Geological time scale Reference: Press et al., 2004, Chapters 1 and 10; Grotzinger et al., 2007, Chapters 1 and 8 (p 183-184) A) How Long is long? Geological time is unlike normal time, at least the time that you and I am familiar with. We are talking Time (with a capital T) and it is long. Most people cannot fathom the ages that geologists must deal with. To you, a long time may be 25 years (the age your car must reach to be get those trending antique license plates), or 100 years (the age your dining room table must be in order to claim it as an antique). Some people consider my lectures to be too long (50 minutes). But geologists deal with billions of years. The late Great Carl Sagan used to talk about billions and billions of stars; geologists talk about billions of years. The Earth is regarded by geologists as being some 4.6 billion years old. The oldest rocks that we have found on the Earth are about 4.1 billion years. The first organic materials (bacteria) appeared some 3.685 billion years ago. These are just numbers, but boy are they big numbers. There are several ways that you can illustrate how big these numbers are. You may have seen me do this in the lecture by using a tape measure. Another good way is by using money. To be more specific, a big bag of pennies. Question: How high would a pile of pennies be that represented the age of the Earth (1 penny per year) if you stacked them up in a single column? Solution: First of all, let’s assume that it is possible to withdrawal $46 million dollars worth of pennies from your local bank. Each penny is approximately 1.5 mm thick (0.06
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This note was uploaded on 02/04/2012 for the course GLY 111 taught by Professor Haywick during the Fall '11 term at S. Alabama.

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111-25 - GY 111 Lecture Notes D. Haywick (2008-09) 1 GY 111...

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