MUSIC 2F03 Lecture Notes - Lecture 3: Continental Drift, Continental Crust, Plate Tectonics

• School: McMaster University
• Department: Music
• Course: MUSIC 2F03
• Professor: Andrew Mitchell

Document Summary

There is much evidence of the continental drift, but a mechanism is needed to explain how/why. Paleomagnetic evidence: magnetic minerals in lava rotate align with earths mag. Field: lava cools, small magnetite (mini magnets) minerals freeze in place, tilt of magnetic. Minerals depends latitude: equator magnet pulled equally each dir, from rocks we can reconstruct how far away poles were & their dir. Until ww2 no picture (detailed) of the oceacn: &0% of the worlds surface. Conclusion: oceanic crust is pulling apart at mid-ocean ridges (mor), collapsing in the central rift valley forming fracture zones. Regions encircled by seismic (earthquake) belts are thin, rigid, slab of crust = The north america plate is bound by a divergent boundary east and convergent and transform boundaries west. Ocean crust = thinner but denser than continental crust. Old plate get recycled because they are older, colder and in effect denser (the colder the crust, the more dense)