GEOL 1425 1ST Edition Lecture 24Outline of Last Lecture I. Wind as an agent of deposition,II. Types of dunes,III. Where deserts are found,IV. Desertification Outline of Current Lecture I. About glaciers, II. Formation of glaciers,III. How glaciers moveCurrent Lecture— Glaciers 1**not yet sure when our final is, but hopefully he will let us know Tuesday!I. About glaciersa. Cover about only 10% of earth’s surfaceb. Valley glaciers—like rivers of ice and move downwards but produce different landforms. Massive occupying full valleys and carving out landc. Continental glacier—in Antarctica and Greenland. Slow-moving and all merge together in one continuous ice sheet where you can’t see any glaciers at all, usually covers the entire land surfaced. Greenland ice sheet is large but Antarctic ice sheet is much largerII. Formation of glaciers a. If there is not a continuous buildup of snow over time, a glacier will not form. These 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.b. Mountain glaciers—form high up in mountains where there is constant snow accumulation and when it is think enough it will start to movec. There must be a cold environment along with a wet/moist one (windward side ofmountain is the moisture-laden and leeward side is typically dry and un-glaciated). Coldest climate is not necessarily the one with most snowd. First fresh snowfall, turns into dense granular snow, firm snow, ice deep down becomes compact from pressure, further burial and aging cause solid glacial icee. Can take between a few years or 10-20 years usually. When ice accumulation is enough for movement, the glacier is formed. Altitude and gravity have an impacton thisf. Ablation mechanisms: i. Melting-loses ice ii. Ice calving- major wastage form causing iceberg formationiii. Sublimation- transfer from solid ice to gaseous state, with no liquid state in betweeniv. Wind erosion- by strong windsIII. How glaciers movea. They don’t all move across equally. Move downhill from their own weightb. basal slip- movement across rock, plucking of bedrock by ice being frozen to the ground. As ice moves forward it gets ripped out by rock. Melting of ice increasespressure so there is water at bottom of these glaciers with water helping it move (lubricant). c. Plastic flow- how the ice itself moves, the individual crystals of ice moving. Most important in very cold ice below freezing
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