GEOL 106 Lecture Notes - Lecture 4: San Andreas Fault, Seafloor Spreading, Continental Crust

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 106
• Professor: Treena Bron

Document Summary

Measure the cha(cid:374)ge of earth"s (cid:373)ag(cid:374)etic crystals. When lava cools, iron bearing minerals align themselves with magnetic north. Polar reverses in the past (north pole wasn"t always north pole) Seafloor spreading: magnetic anomalies on sea floor, measured using a magnetometer, as magma wells up in ocean ridge, it creates new rock that spreads rock out. Hydrothermal vents: believe some of earliest signs of life started here. Outer shell of earth divided into plates. About 20 plates (7 or 8 major ones) About 100 km thick composed of rigid lithosphere (upper most mantle and crust) Many plates have both oceanic and continental crust. Plates are in motion, the plate moves as a unit carried over the weak and plastic atmosphere. Not permanent features, size and shape change. Most major tectonic activity occur at plate boundaries. Three types of plate boundaries: divergent. Continents are carried along with the crust.