GEOL 1 Lecture Notes - Lecture 2: Mid-Ocean Ridge, Oceanic Crust, Divergent Boundary
Document Summary
Lithosphere: the crust and the uppermost part of the mantle are relatively rigid. Asthenosphere: the upper most mantle underlying the lithosphere, is soft and therefore flows more readily than the underlying mantle. Provides a lubricating layer over which the lithosphere moves (asthenos means weak) Where hot mantle material wells upward it will uplift the lithosphere. Where the lithosphere is coldest and densest, it will sink down through the asthenosphere and into the deep mantle. Tectonic forces: the effect of this internal heat engine on the crust is of great significance to geology. The forces generated inside the earth, called tectonic forces, cause deformation of rock as well as vertical and horizontal movement. Plates pulling apart (divergent): creation of new ocean floor with submarine volcanoes. 3 main plate boundaries oceanic ridge, small to moderate earthquakes. Plates pulling together (convergent): destruction of ocean floor; creation and growth of mountain range with volcanos, subduction zone, earth"s greatest earthquakes and tsunamis.
