GLACIAL PROCESSESAIM• Explain how glaciers erode, transport and deposit to create landforms in the TVC
Glaciers• A glacier is very slow moving river of ice• Meltwater (underneath the frozen ice) allows the glacier to slide over the ground and then move downhill due to gravity• A top of a glacier looks cracked, theses are called crevasses.• These cracks are formed due to the stress as the ice is pulled and moves at different speeds
Glaciers ERODE• A glacier erodes the valley floor and sides by plucking and abrasionPLUCKING ice touching the sides and ground can thaw slightly and then refreeze around rocks sticking out. When the glacier moves forward, it plucks these rocks awayABRASION debris carried in the glacier can scrape material off the valley walls and floor
Glaciers TRANSPORT• A glacier carries debris that is has plucked away or bits of rock that have been broken off, or fallen onto the glacier.• A glacier transports this debris in 3 waysON TOPWITHINUNDERNEATH
Glaciers DEPOSIT• A glacier deposit their load as they move and meltLATERAL MORAINE is deposited where the sides of the glacier wereMEDIAL MORAINE is deposited in the centre of valley where 2 glaciers meetTERMINAL MORAINE is deposited at the end of the glacier
The Work of Ice• Glue in the sheet labelled – The Work of Ice.• Fill in the gaps on the sheet, using the words belowWhakapapa moraine Whangaehuglaciation freeze-thaw smalltwo cirques centimetresU terminal wintersummer plucks moraine100,000 Proto-Ngaruhoe cinderMangatepopo resistant Ruapehuaccumulates
The Work of IceThe action of ice is known as glaciation. Glaciers begin in hollows known as cirques. Herethe ice accumulates (gathers) and begins to flow. As it flows, the ice plucks rocks from thevalley sides and floor. The action of freeze-thaw also produces small fragments which fallonto the glacier. These fragments carried by the glacier are called moraine.A valley that is carved by a glacier has a characteristic u-shape . The glacier flows at a rateof a few centimetres a year. This tends to advance during winter and retreat duringsummer. A retreating glacier will dump the debris it is carrying to form a terminalmoraine.In the TVC there are two glaciers both on top of Mt Ruapehu. They are called theWhangaehu and Whakapapa glaciers. Both of these are very small in scale.In the past however ice action was much more significant. During the ice ages, approx.100,000 years ago huge glaciers carve the main volcano in the region known as Proto-Ngauruhoe. This covered most of the mountain and carved huge valleys into the softcinder cone. An example of a valley formed this way is Mangatepopo. Only areas of hardresistant lava were not destroyed by the ice.