CAS ES 351 Chapter Notes - Chapter 5: Subduction, Convergent Boundary, Paleomagnetism
24 Mar 2019
School
Department
Course
Professor
Document Summary
Chapter 5: plate tectonics and long-term climate change. The critical reason continents and ocean basins move is because of the way layers of rock behave, not because of differences in elevation, crustal thickness, and composition. The past effects of plate tectonics rearranging our geography can be assessed through our magnetic field. Molten fluids in earths liquid iron core create a magnetic field. Some of earth"s once-molten rock contain fossil compasses that record past magnetic fieldthese froze into rocks after they cooled from a molten state. The best rocks for this are basalts, which are rich in magnetic iron. Basalts form the ocean basins floors and are found on land near tectonic regions. As the rock cools, its iron components align with the magnetic field. Also in the rock are radioactive minerals like potassium that has slow decay and can date when the basalt layers cooled and acquired their magnetic compasses.
