EARTH 205 Lecture Notes - Lecture 13: Basalt, Closed System, Stratovolcano
31 Mar 2019
School
Department
Course
Professor
Document Summary
Elements are determined by how many protons they have (and this then determines. Their basic chemical behavior) but the number of neutrons in the nucleus can. These are the isotopes of an element. That unstable nuclei transform into different elements. To date something very old, should use isotopes with a very long half-life. Mass spec"s (electro magnetic) measure these isotopes. If mountains expose rocks that were once buried deep in the earth, then there must be. Example: sedimentary (limestone) in fayette, mi and yosemite valley. Either rocks moved up, or sea level went down a lot! Intrusive igneous: these rocks were formed at a depth off several kilometers Also, if we accept continental drift/plate tectonics reconstructions, then there are also large-scale* horizontal motions of rocks. Rocks can deform by faulting at shallow depths, but deep deformation is ductile. In particular, rocks must be colder than some tcrit to have brittle failure and possibly earthquakes.
