EARTH 7 Lecture Notes - Lecture 3: Siccar Point, James Hutton, Devonian
Document Summary
Uniformitarianism: the present is the key to the past: physical processes observed today operated in the geological past, slow processes acting over immense time have helped shape earth"s surface. Vertical beds of silurian sandstone: ~425 ma. Overlain by gentle dripping, devonian redbeds: ~345 ma. Tons of missing time: ~80 million years. Millions of organisms have evolved over time. Each group of organisms lived in a discrete time interval. This order is preserved in the rock record. Fossils give us a sense of the relative ages of rocks. Based on the regular radioactive decay of certain isotopes. Stable - balanced number of neutrons and protons. Daughter product: stable isotopes resulting from the decay of a parent. Half-life: the time required for one half of the radioactive parent nuclei in a sample to decay into its daughter product. Oldest minerals on earth ~4. 4 billion years.
