Presentation on theme: "Glaciation Presentation. Alan Doherty Linlithgow Academy."— Presentation transcript:
Alan Doherty Linlithgow Academy
Climate Change is not new! From Glaciers by John Gordon Colin Baxter Publications, 2001
Interglacial periods Glacial periods From Glaciers by John Gordon Colin Baxter Publications, 2001
Snow 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 layers Pressure gradually turns the snow into ice When the critical mass of ice is reached, the ice begins to move downhill A glacier is born!
Snowflakes are compressed and squeezed into ice crystals n.b. the colour changes from white to blue!
How does ice flow? With difficulty!
GLACIATION 2. THE SNOW COMPACTS INTO ICE 3. THE ICE FLOWS DOWN THE MOUNTAINSIDE 4. THE GLACIER PUSHES FORWARD AND MELTS BACK 1.SNOW BUILDS UP IN HOLLOWS IN THE HILLSIDE
Valley Glaciers Denali, in Alaska nasa
Ice Sheets From Earth from Above by Yann Arthus-Bertrand
If the ice covers the whole area then the mountain tops are rounded e.g. Scotland If the mountain tops remain above the ice then frost action makes them jaggy. e.g.the Alps
Past and Present Ice Limits From Earth Story By Lamb and Sington
GLACIATION GLACIERS ERODE TRANSPORT and DEPOSIT
Glacial Erosion Glaciers erode in two ways Abrasion - this occurs when stones embedded in the bottom of the glacier scrape across the ground Plucking - 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.
Glacial Erosion Cirque = Corrie = Cwm From A2 Geography for AQA specification A by Bowen, A & Pallister, J. Reprinted by permission of Harcourt Education
Aretes or sharp ridges corrie tributary glacier main glacier arete
A corrie is a hollow in the hillside Corrie or cirque Lochan or tarn arete Mountain top End moraine
Aretes and pyramidal peaks Pyramidal peak Arete ridge
Hanging valley Misfit stream
Transportation Material which is carried along by the ice is called moraine. Large stones which are dropped as the ice melts are called erratics.
From A2 Geography for AQA specification A by Bowen, A & Pallister, J. Reprinted by permission of Harcourt Education
Deposition by ice: moraine by water: fluvio-glacial
Deposition by ice: moraine ( boulder clay) by water: fluvio-glacial ( sands & gravel)