GEOL 108Lg 1st Edition Lecture 2Outline of Last LectureI. SeismologyII. Seismic Wavesa. S waves and P wavesIII. Refraction and ReflectionIV. IsostasyV. Continent-Ocean DichotomyVI. Magnetic AnomaliesVII. Seafloor SpreadingOutline Current Lecture I. Mid Ocean RidgesII. Convection CurrentsIII. Rayleigh Number and its MeaningIV. Mantle PlumesV. Plate Motiona. Plate Boundaries/TypesCurrent LecturePlate Tectonics, Part TwoA Mid-ocean Ridge: Underwater mountainous region formed by plate movement. This uplifting of the ocean floor as demonstrated by the above image occurs when convection currents rise inside the mantle underneath the oceanic crust and create a sort of line of magma where two separate tectonic plates meet at a boundary. Convection currents are caused as a result of the hot material at the deepest part of the mantlerising, cooling, sinking, and then heating, rising and repeating the cycle.Rayleigh #The Rayleigh number is a dimensionless number associated with buoyancy; tells you whether the heat transfer occurs in the form of conduction or convection. A high Raleigh number signifies the more vigorous the convection. If it is above 1,000, the more the system likes to convex. High Raleigh numbers mean an increased likelihood for a mantle plume to come up.Mantle Plumes and hotspots are not found at plate boundaries. Plume head piles up beneath the plate, flood basalts. Hot mantle rock that rises toward the surface of the earth is called a mantle plume. Plate MotionAbove is a photo of the motions of the plate tectonics. The black lines signify plate boundaries. There are three types of plate boundaries:- Divergent Boundaries: These boundaries create new crust as two or more plates pull away from each other.- Convergent Boundaries: In this boundary type, crust is destroyed and recycled back into the interior of the Earth as one plate dives under another. This creates what we have already discussed to be subduction zones. There are 3 types of convergent boundaries: Oceanic-Continental Convergence; Oceanic-Oceanic Convergence; and Continental-Continental Convergence.- Transform-Fault Boundaries: These types of boundaries are where two plates are sliding horizontally past one another. These are known commonly as
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