Formation and MovementPleistoceneGlacier GeomorphologyLand Forms from Continental GlaciationErosionDepositionGEO 155 1st Edition Lecture 21Last Lecture Streams as Geomorphic AgentsOutline of Current LectureI. Glaciersa. How they form and moveb. Erosion and Depositionc. Land forms of continental glaciationCurrent LectureFormation and Movement- Cold, snowy winters- Cool summers- Net accumulation of snow, squeezes air out of cracks until it turns to ice, heavy weight of ice causes itto deform and move out from under the pressureo Takes at least 60 feet of ice to start movingo Known as the zone of accumulationo Might move out (“advance”) of this area into an area without net accumulation Known as the zone of ablationo Boundary between the two zones is known as the equilibrium line If this boundary shrinks, the glacier “retreats” or recedeso Occurs at high latitudes and altitudesThese 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.Pleistocene During the Pleistocene (“Ice Age”) that occurred 2.5 million to 11,000 years ago, a continental glacier covered most the North America- Alpine glaciers covered the mountains- Relic land forms covered the landscape and were leftover when the ice passedGlacier Geomorphology- Plucking – rock holds onto cold glacial surface and freezes to it, glacier moves and pulls the rock out ifthe rock is weakero Most effective area of the rock to pull from is an area with many crackso The more a glacier erodes, the better it gets at eroding due to the accumulation of rocks creating a rough friction bottom- After causing erosion, the glacier transports the eroded material, it then deposit this material known as glacial drift in the zone of ablationo There are two types of glacial drift namely: Glacial till – deposited by melting ice and material is unsorted- Accumulation of till is moraine Outwash – reworked by melted water and material is sortedLand Forms from Continental GlaciationErosion- Ice-scoured plaino Flato Thin soilso Mainly lakes due to pluckingDeposition- Generally flat- Terminal moraine – end of glacial ice- Recessional moraine – new ridge forms from melting at warmer areaso Deposited when glacier was retreating- Ground moraine – layer of till that is flat because the ice did not stay long enough for much accumulation- Drumlins – steep wide hill of ice that narrows at the end of the ice’s path- Kame – when there is a hole in the ice, water runs in, sediment that it carries piles up in the hole, ice melts leaving a pile of sediment known as kame- Esker – stream runs in a tunnel within ice, but there is not enough energy to move all of the sedimentso it piles up, when the ice melts, it leaves behind a long-winding ridge in the shape of the stream’s path known as esker- Kettle – at the edge of the glacier, deposited till collects a block of ice from the glacier that broke off, more till collects around it, while it melts a depression is created in the moraine known as a
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