GEOL 101 Lecture : Geology 101 Lab Day 1.docx
18 Sep 2014
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Seafloor spreading: early 1960s, harry hess suggested that new oceanic crust are created in oceanic ridges such as the mid atlantic ridge, as the process goes on the seafloor, the floor is carried apart like a conveyor belt, he also suggested crust descends in the vicinity of deep ocean trenches, seafloor spreading combined with a greater understanding of remnant magnetism preserved in oceanic rocks developed into the unifying theory called plate. Earth"s layered structure: crust, mantle, core, all have a distinct chemical composition, crust, 5 70 km (top layer, mantle, 2900 km, core, 3480 km, the lithosphere is the rigid outer shell of earth, 100 km, the temperature pressure regime in the upper asthenosphere result in a fluid like behavior. Plate boundaries: divergent, 2 plates move apart, ex: mid atlantic ridge, convergent, plates moving together, several types of convergent margins, can cause volcanic eruptions, two continents can collide.
