GEOL 108Lg Lecture Notes - Lecture 10: Fault Scarp, Radiometric Dating, Outer Core
Document Summary
Time in the earth sciences: relative versus absolute time. Relative age dating using fossil record geological time scale (knew if rock was older or younger than other rock. Uranium 238- pb 206 (measure half life-4. 49 billion years) Carbon 14 nitrogen 14 (5570 years half life) To date fossils would use 40k or 238u: half-life of an unstable isotope. 4. 6 billion years ago stars are moving away from earth further away=faster moving (red shifted- away from us; blue shifted-towards us) With velocity and distance we can track where they came from. Know age of earth from radiometric dating of stony meteorite (carbonaceous condrites)-never been heated over a few 100 degrees/part of another planet. Age of the universe ~15 billion years ago- can tell because we can observe the speed and direction at which galaxies are moving and can figure they started at the same place and the same time-the big. Earth: layered planet because of gravitational differentiation.
