1. Glaciers (chapter 11 in Summerfield) Permanent (on human timescales) body of ice, consisting largely of recrystallized snow, that shows evidence of downslope or outward movement due to pull of gravity. ~10% of surface of continents covered by ice today, but ~30% covered as little as ~18,000 years ago (landforms, sediments, isostasy, climate records) Glaciers responsible for huge amounts of erosion in high-elevation terrain (although processes tough to observe, poorly understood)

2. Glaciers (chapter 11 in Summerfield) Form depends on competition between accumulation and melting of ice Snow accumulates and compacts to form ice, but ice doesn’t sit still… it deforms plastically (handout)

3. Crevasse

4. Types of glaciers (1)Temperate vs. Polar (2) Alpine or mountain glaciers Valley glaciers Cirque glaciers Fjord glaciers Ice caps or ice sheets or continental glaciers Today, only Greenland and Antarctica Their combined mass is 95% of ice on Earth Melt would cause 200 ft sea level rise Can have ice shelves (floating ice at coast)

5. Small scale erosional features: Glacial striations & polish Glacial Erosion

6. Cirque Glacial Erosion

7. Cirque Glacial Erosion

8. Cirque: North Cascades Glacial Erosion

9. Fjords, Greenlandorth Cascades Glacial Erosion

11. U-shaped valley, hanging valleys Glacial Erosion

12. Arete North Cascades Glacial Erosion

13. HornNorth Cascades Glacial Erosion

15. Glacial Deposits Till: unsorted glacial sediment

16. Glacial Deposits Yeager Rock, a 400 ton erratic on the Waterville Plateau, Washington

17. Glacial Deposits Lateral moraine, Switzerland

18. Glacial Deposits Lateral moraine, Switzerland

19. Glacial Deposits Dropstones: Ice-rafted glacial debris

20. Glacial Deposits Glacial outwash - sediment choked streams from melting glacier form braided streams, deposit poorly sorted, stratified sediment Iceland

21. Esker: long, winding ridge of stratified sand and gravel Why????

22. Esker: long, winding ridge of stratified sand and gravel Why????

23. Drumlin Glacial landforms

24. Drumlins Glacial Erosion

25. Glacial landforms Kettle lakes: depressions under glacier remain after glacier melts Siberia

26. Puget Map Glacial Landscape

27. J Harlan Bretz and the Channeled Scablands

28. What processes link climate change, glaciers & sea level? Eastern Juan de Fuca Strait was filled with ice prior to 13,000 years ago (13 ka). The area was isostatically depressed. When climate warmed and the ice melted ~12 ka, how did local RELATIVE SEA LEVEL change? time local sea level

29. Relative sea level curve, Juan de Fuca Strait (Mosher et al., 2004) Global eustatic sea level curves (Fairbanks, 1989; Peltier, 2002)

30. Relative sea level curve, Juan de Fuca Strait (Mosher et al., 2004) Rapid isostatic rebound causes local relative sea level to drop rapidly As rebound slows, effect of global (eustatic) sea level rise wins out, causing local sea level rise