Glaciers, Ice AgesGlaciersSouthern HemisphereNorthern HemisphereIce Age Sea Level on North AmericaValley and Piedmont GlaciersCrevasseGlacier movement, tracked by stakesGlacial Snow BudgetStriations and polishCycle of valley glacier erosionU-Shaped Valley with tarnsHanging ValleyAreteCirque, HornFiordLateral moraineLateral and Medial MoraineMoraine depositLoessContinental Glacial depositsPleistocene Ice MaximumUpper Midwest End MorainesCoastal moraines of New EnglandUpper Midwest drainage before glaciationUpper Midwest Drainage—after glaciationPluvial Lakes of SouthwestIce Age Sea Level on North AmericaIceberg PhotoIceberg diagramBering land bridgeLocation of 300 MY Continental GlaciationLocation of 300 MY Continental Glaciation with continents located 300 myaES 106 Final ExamElliptical orbitAxial Tilt variationobliquityPrecession of axial tiltMilankovitch cyclesNorthern hemisphere insolation differences due to Milankovitch cyclesOxygen isotope fractionationTemperature record from O-18Threshold diagramPositive Climate Feedback LoopsIce-albedo feedback loopPositive Climate Feedback LoopsNegative Climate Feedback LoopForest cover—negative feedbackTemperature compared to sulfur aerosol concentrationNutrient cycleNutrients related to sea level changePast Glacial AgesPast Glacial AgesGlaciersEarth ScienceChapter 6p. 154-159, 168-173Southern HemisphereNorthern HemisphereIce Age Sea Level on North AmericaValley and Piedmont Glaciers• Malaspina Glacier, AlaskaCrevasseGlacier movement, tracked by stakesGlacial Snow BudgetStriations and polishCycle of valley glacier erosionU-Shaped Valley with tarnsHanging ValleyAreteCirque, HornFiordLateral moraineLateral and Medial MoraineMoraine depositLoessContinental Glacial depositsPleistocene Ice MaximumUpper Midwest End MorainesCoastal moraines of New EnglandUpper Midwest drainage before glaciationUpper Midwest Drainage—after glaciation• Deranged drainage after ice meltsPluvial Lakes of SouthwestIce Age Sea Level on North AmericaIceberg PhotoIceberg diagramBering land bridgehttp://www.atmos.washington.edu/~dennis/Our_Changing_Climate.htmlLocation of 300 MY Continental GlaciationLocation of 300 MY Continental Glaciationwith continents located 300 myaElliptical orbitAxial Tilt variationobliquityPrecession of axial tiltMilankovitch cyclesNorthern hemisphere insolation differences due to MilankovitchcyclesOxygen isotope fractionationTemperature record from O-18Threshold diagramPositive Climate Feedback Loops• Ice albedo decreases temperature, increases ice. Reduced ice increases temperatureIce-albedo feedback loopPositive Climate Feedback Loops• Ice albedo decreases temperature, increases ice. Reduced ice increases temperature• Glacial periods result in larger arid areas, increasing delivery of iron nutrients to sea, lowering CO2levels, and temperature• Lowering sea level will expose reefs to weathering. Reaction consumes CO2, lowering temperature. Rising sea level has opposite effectNegative Climate Feedback Loop• Forest die out during glacial ages, reducing mechanism to remove CO2from atmosphere, increasing temperatureForest cover—negative feedbackTemperature compared to sulfur aerosol concentrationNutrient cycleNutrients related to sea level changePast Glacial Ages• Pliocene-Pleistocene– Ice in Antarctica starting about 40 m.y.a.– Widespread N. Hemisphere ice about 3 mya– Advances every 40,000 to 100,000 years• Karoo Ice Ages– 260 to 350 mya– Lasted 90 million years– Wegener’s evidence of continental movement• Andean-Saharan Ice Ages– 430 to 460 mya– Lasted 30 million years• Cryogenian– 630 to 850 mya– Lasted 200 million years– Periods of all Earth covered with glacier• Huronian– Over 2 billion years ago– Lasted 300 to 400 million yearsPast Glacial
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