Geo 101N 1st Edition Lecture 7Outline of Last Lecture I. Magnetic AnomaliesII. Plate Tectonics continueda. Acceptanceb. Plate Layersc. MarginsOutline of Current Lecture III. Plate TectonicsIV. Lithospheric LayersV.Margins continuedVI. Earthquakes and BoundariesCurrent LectureIII. Plate Boundariesa. Breaks in the lithosphere define boundaries of 7 major tectonic platesb. Plates are rigidc. 1 plate can consist of continental and oceanic crustIV. Lithosphere: once mantle rock cools below 1280ᵒ it becomes, by definition, part of the lithospherea. Continental ~150kmi. Graniteii. Less buoyantiii. Floats higherb. Oceanic ~7-100kmi. Basaltic crust→7-10km thickii. Heavier (more dense)iii. Less buoyant, sinks faster than continental crustV. Continental Marginsa. Where land meets oceanb. Active boundaries→near plate boundariesc. Passive boundaries→not near a plate boundary; continental crust thins seaward; transitions into oceanic crust and traps eroded sedimentVI. Earthquakes and Boundariesa. Plate boundaries are most easily identified by earthquake concentrationb. Plate interiors are almost EQ freeThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. EQ characteristics depend on the cause of the EQVII. Boundary Types (beginning)a. Divergent: spreading ridgesi. Opens @axial rift valley; asthenosphere melts, forming mafic magmaii. Pillow lava: forms when lava erupts
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