GEO 102 Lecture 11 Outline of Last Lecture I. How the Earth worksOutline of Current Lecture II. Geologic Time III. How old is thatIV. How do we knowV. Relative dating and basic principles of rock formationsCurrent LectureGeologic Time-If you live to be about 80 years old, that means that you have lived only a bit more than one ten millionth of 1 percent of the age of the earth.-Earth is 4.55 billion years oldHow Old is That?-If we think of the age of the earth as a roll of toilet paper, each sheet would represent 4,500,000 years!-If a football field represented the earth’s age, the entire history of civilization would fit into less than 1/5 of one millimeter.-less that one blade of grass-edgewise!How do we know?-There is a long history of discovery concerning the age of the Earth-Scientists long suspected that the Earth was ancient but it was a radical idea to everyone else -In the late 1700s to early 1800’s this became well-established with relative datingThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Relative Dating-Sequence of formation – Steno’s laws (not trying to put a number on it, just sequence)-Still a very valuable tool-Application basic logical principlesBasic Principles of Rock Formation- superposition: In an undeformed sequence of sedimentary rocks, each layer is older than the one above, and younger than the one below.-Try inserting sand underneath other sand without disturbing
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