2GlaciationStandard GradeGeographyAlan Doherty Linlithgow Academy
3Climate Change is not new! From “Glaciers” by John GordonColin Baxter Publications, 2001
4Interglacial periods Glacial periods From “Glaciers” by John Gordon Colin Baxter Publications, 2001
5Snow collects in hollows Snow builds up during the winter (accumulation) and melts during the summer (ablation)If accumulation is greater than ablation the snow builds up in layersPressure gradually turns the snow into iceWhen the critical mass of ice is reached, the ice begins to move downhillA glacier is born!
6Snowflakes are compressed and squeezed into ice crystals n.b. the colour changes from white to blue!
81.SNOW BUILDS UP IN HOLLOWS IN THE HILLSIDE GLACIATION1.SNOW BUILDS UP IN HOLLOWS IN THE HILLSIDE2. THE SNOW COMPACTS INTO ICE3. THE ICE “FLOWS” DOWN THE MOUNTAINSIDE4. THE GLACIER PUSHES FORWARD AND MELTS BACK
10Ice SheetsFrom “Earth from Above” by Yann Arthus-Bertrand
11If the ice covers the whole area then the mountain tops are rounded e If the ice covers the whole area then the mountain tops are rounded e.g. ScotlandIf the mountain tops remain above the ice then frost action makes them “jaggy” e.g.the Alps
12Past and Present Ice Limits From “Earth Story”By Lamb and Sington
14Glacial Erosion Glaciers erode in two ways Abrasion - this occurs when stones embedded in the bottom of the glacier scrape across the groundPlucking - this occurs when the bottom layer of ice freezes on to the ground when the ice is stationary. When the glacier begins to move, bedrock material may be torn from the ground.
15Glacial Erosion Cirque = Corrie = Cwm From “A2 Geography for AQA specification A” by Bowen, A & Pallister, J. Reprinted by permission of Harcourt EducationCirque = Corrie = Cwm
16Aretes or sharp ridges arete corrie corrie tributary glacier main glacier
17A corrie is a hollow in the hillside areteEnd moraineCorrie or cirqueLochan or tarnMountain top