Earth Sciences 1022A/B Lecture Notes - Lecture 7: Metamorphic Rock, Unconformity, Nonconformist
14 Apr 2016
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Superposition: each bed is older than the one above and younger than the one below. Original horizontally: sediment is usually deposited horizontally. Cross-cutting relations: a fault is younger than the rock it cuts, a rock is younger than the rock it cuts. Inclusions: inclusions are older than the rock containing them. Angular unconformity: between flat and titled, eroded beds. Non-conformity: between flat beds on eroded igneous, metamorphic rock. Fossil succession: organisms evolved along distinct pathways through geological time, left index fossils. Radioactive isotopes (parents) decay to daughters over time. Time it takes to decay t half the amount of parent is left is the half life of the isotope. Compare parent left with the half life, gives time since rock formed. Oldest rocks on earth are found in canada. In organisms c14 decays to n14 with half life of 5730 years but is replaced by c14 from the air.
