GEO 110 Lecture Notes - Lecture 5: Seismic Wave, Continental Crust, Oldest Dated Rocks
30 Nov 2016
School
Department
Course
Professor
Document Summary
Principle of superposition: rock and sediment are always arranged with the youngest bed (cid:498)superposed(cid:499) towards the top of a rock formation and the oldest at the base, if they have not been disturbed. This is how scientists learned about the age of the earth. How old is earth? sun and its solar system estimated to have occurred more than 4. 6 billion years ago. Present thinking places earth that 4. 53 billion years. Holocene: youngest epoch in the geologic time scale, characteristic of postglacial conditions since the retreat of continental glaciers, about 11500 yrs ago. two facts: 1. Oldest rock on earth about 4 billion years old, 2. Oldest fossil on eart about 3. 5 billion years old radiometric dating: half life, the decay-rate is the time required for one0half of the unstable atoms in a rock. Present is key to the past the same physical processes active in the environment today have been operating throughout the geologic time.
