1. Glacial Erosion features Ribbon Lakes Objectives: To understand the formation of the following glacial erosion features: Ribbon lakes To know the terms: truncated spurs, alluvial fan

2. TARN 5 RIBBON LAKE 13 erosion 4 ABRASION 7 GLACIAL TROUGH 11 ACCUMULATION 18 BERGSCHRUND 17 FREEZETHAW 10 ROTATIONAL SLIP 1 SNOUT 8 HANGING VALLEY 15 PLUCKING 19 BACKWALL 16 PYRAMID PEAK 14 MORAINE 6 CORRIE 20 ABLATION 9 CREVASSE 2 ARETE 12 WEATHERING 3

3. Ribbon Lake

4. Ribbon Lakes Many glacial troughs contain long, anwrro ribbon lakes. They may be the result of: (i) sreioon when a reicalg over-deepens part of its alylev in an area of softer okcr . (ii) a glacier over deepening its valley due to increased erosive power after being joined by a ibuttarry glacier (iii) deposition of aeimnor across the main valley forming a dam. When the glacier retreats, the deepened sections fill with melt water and become lakes. These lakes remain after glaciation, supplied by rainfall, streams and rivers. There are a number of examples of ribbon lakes to be found in the Lake District.

5. Lake Windermere

6. Can you identify a corrie, pyramid peak, hanging valley, terminal moraine, corrie lip, arete, glacial trough? In summary….

7. - grooves on rock created by abrasion due to debris embedded in base of glacier - Sharp, pointed hilltop between three or more corries (e.g. Snowdon, N Wales) - large armchair shaped hollow enlarged as ice moves in a rotational movement under gravity (e.g. Cwm Idwal, Glaslyn, North Wales) - Knife shaped ridge between two corries (e.g. Grib Goch, N Wales) Striations Corrie (Cirque) Arête Pyramidal Peak Ribbon Lake - long narrow lake occupying an area of the trough floor which has been overdeepened (e.g. Llyn Ogwen, Snowdonia)