1 Calving Ice 2 Glacial erosion Glaciers erode and transport sediment Abrasion Plucking 3 Glacial erosion Glacial abrasion Rocks within the ice act like sandpaper to smooth and polish the surface below Rock flour (pulverized rock) Glacial striations (grooves in the bedrock) Glacial polish 4 Glacial Striations 5 Striations 6 Glacial polish 7 Abrasion and Plucking, Yosemite National Park, CA Fig. 12.20, p. 343 8 Glacial deposits Glacial drift – nonstratified, nonsorted drift deposited directly from glacier ice 9 Glacial Deposits erratic _ a glacially_transported rock fragment different from the surface upon which it lies. 10 Glacial drift Till – material that is deposited directly by the ice Outwash – materials deposited by meltwater streams coming off a glacier 11 Glacial till is typically unstratified and unsorted Fig. 12.21, p. 344 12 Glacial till 13 Glacial deposits: Landforms made of till moraine _ an accumulation of drift built up chiefly by the direct action of ice. 14 Glacial deposits: Moraines DEF.: end moraine _ a ridge of drift that marks a point in the advance or recession of a glacier. DEF.: terminal end moraine _ the end moraine marking the farthest advance of a glacier. 15 Glacial deposits: alpine Lateral moraines 16 Lateral moraine 17 Lateral moraines
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18 Glacial deposits: alpine Medial moraines 19 Medial and Lateral Moraines 20 Medial moraines 21 Glacial deposits Ground moraine Fig. 12.27, pp. 348-349
22 Long Island is made up of end moraines Fig. 12.26, p. 347 23 Glacial deposits Landforms made of till Drumlins • Smooth, elongated, parallel hills • Steep side faces the direction from which the ice advanced
24 A drumlin, upstate New York 25 Drumlins, Fig. 12.28, p. 350 26 Drumlin field 27 Glacial deposits Ice Thrust Masses Ice plucks a LARGE piece of bedrock Hill and neighboring depression • Devil’s Lake (Sully’s Hill to the South) • Sibley Buttes of Kidder County • Region of Anamoose 28 Glacial deposits Landforms made of stratified drift: Outwash plains Often pockmarked with depressions called kettles Fig. 12.27 29 Glacial deposits Diagram of how kettles are formed 30 Glacial deposits Def.: Kettle – a closed depression in a deposit of drift, formed when a block of ice is buried and later melted
31 32 Glacial deposits Landforms made of stratified drift: Ice-contact deposits Deposited by meltwater flowing over, within, and at the base of motionless ice Include:
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33 Glacial deposits Diagram of how eskers are formed
34 Glacial deposits Def: Esker – a sinuous ridge of stratified sand and gravel formed by subglacial stream action
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37 38 Glacial deposits Diagram of how kames are formed
39 Glacial deposits Def.: Kame – a body of stratified drift shaped as a short, steep-sided knoll or hummock
40 Glacial Erratics 41 Erosional features of glaciated valleys Fig. 12.13, p. 339 42 U-Shaped, V-shaped, and Hanging Valleys 43 Hanging valley 44 Hanging Valley 45 Fig. 12.13, p. 339 Cirques, Arêtes, and Horns 46 Alpine View 47 Cirque 48 Arête wall Fig. 12.13, p. 339 49 Pater Noster Lakes and Tarns 50 Pater Noster lakes 51 Pater Noster lakes 52 Fiord 53 Fiord 54 The Matterhorn 55 The Matterhorn
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