Alpine Glaciers

1. Alpine Glaciers Ice that flows down mountain valleys (e.g. in the Alps!)

2. Mont Blanc, near Chamonix, France - note the alpine glacier that flows to lower elevations, nearly reaching the main valley in which Chamonix lies

3. Bergschrund at head of a glacier above Chamonix

4. Mer de Glace above Chamonix - note ogives

5. Rockfalls from the valley walls add debris to the glacier’s surface

6. Glaciers are capable of carrying debris of almost any size - from the fine particles embedded in the ice in the foreground, to the huge angular boulder in the background

7. Landforms of Alpine Glaciation U-shaped valleys Cirques, Aretes, Horns Moraines Striations

8. Mer de Glace • An alpine glacier, whose flow is confined to a valley • Such glaciers are very efficient at eroding their valleys, widening and deepening them into classic U-shaped valleys

9. Fjord - a glacially eroded valley invaded by the sea

10. Cirques are high basins where alpine glaciers originate Horn Arete Cirque

11. The Grand Teton (WY) is a classic horn - note several small cirques that have eroded into the mountain, leaving only a fairly narrow, jagged peak.

12. Iceberg Lake (Glacier National Park, MT) occupies a cirque The sheer rock face at the back of the cirque is an arete - a narrow ridge between two cirques that have eroded back into the mountain from opposite sides

13. Portage Glacier (AK) - note lateral and medial moraines

14. Medial moraines form where glacial tributaries merge

15. End moraines form at the terminus of a glacier

16. Cirques with small residual glaciers in the Lyman Valley, WA Note the end moraines, built of debris deposited by the glaciers when they extended a bit further downslope during the “Little Ice Age” (~1550-1850)

17. Glacial Abrasion • Debris carried at the base of a glacier can smooth and scratch the bedrock it flows over - the scratches are called striations