lecture_17_glaciers

lecture_17_glaciers - GLACIERS GEO 1115 Introduction to...

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GLACIERS GEO 1115 – Introduction to Earth systems Lecture 17
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Key terms acier rque glacier snow line firn cirque arête U-shaped valley zone of accumulation equilibrium line zone of ablation fjord grooves triations ablation calving astic flow sa o s pothole drift (unstratified, stratified) l plastic flow basal slip velocity profile till esker drumlin dry-based glacier wet-based glacier GEO 1115 – Introduction to Earth systems Lecture 17
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GLACIERS – Pre-lecture questions • What percentage of the planet’s freshwater is trapped in glaciers? • Why is it cold at the poles? • Is ice a fluid? • Is ice a rock? GEO 1115 – Introduction to Earth systems Lecture 17 2.15%
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utline Outline 1- What is ice (rock, fluid)? 2- Why are glaciers important? ow do glaciers form? 3- How do glaciers form? 4- How do glaciers move? 5- How are glaciers classified? 6- What landforms and deposits are formed by glaciers? laciations in Earth’s history GEO 1115 – Introduction to Earth systems Lecture 17 7- Glaciations in Earth s history
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Hydrologic cycle (review) Distribution of Earth’s water Oceans: .2% ctures 14 &15 1. Oceans: 2. Freshwater: 97.2% 2.8% Lectures 14 &15 2a. glaciers: oundwater: 2.15% Today’s lecture 2b. 2c. groundwater: other 0.62% Lecture 13 lakes: atmosphere: soil moisture: 0.009% 0.005% 0.001% Lectures 17 & 18 GEO 1115 – Introduction to Earth systems Lecture 17 streams: 0.0001%
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% of hydrosphere ~ arth’s freshwater Importance % ~2% of hydrosphere, ~ Earth s freshwater Greenland ntarctica 80% Antarctica laciers cover 10% of land surface (95% shown in the two figures above) GEO 1115 – Introduction to Earth systems Lecture 17 Glaciers cover ~10% of land surface (95% shown in the two figures above) 95% of earths glaciers - on this slide
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What is ice? Is ice a rock? 1) Is ice a rock? Solid coherent substance made up of many ice crystals (why is ice a mineral?) e under the ice under the microscope igneous rock hy? Ice is like: an igneous rock – Why? a sedimentary rock – Why? metamorphic rock hy? GEO 1115 – Introduction to Earth systems Lecture 17 a metamorphic rock Why? - ice is a mineral - must be hard, inorganic, natural, contant chemical composition and crystalline - together, ice is a rock - made of minerals - igneous - cools from liquid - sedimentary - laid down from layers that have accumulated - metamorphic - made from burial metamorphism - compression of snow into ice
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What is ice? 2) Is ice a fluid ? Fluids: • deform under … ve the ability to • have the ability to … GEO 1115 – Introduction to Earth systems Lecture 17 - shear stress - shear stress - deformation can occur from own weight over a large time scale flow
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What is ice? Velocity vectors showing glacier flow kobshavn Greenland Jakobshavn, Greenland Kalstenius Ice field, Ellesmere Is. GEO 1115 – Introduction to Earth systems Lecture 17 Nasa / Goddard space flight center - not static - blue lines are velocity vectors - lengthen in the narrower passages - second image - there is movement - can tell due to the formations of tributaries - movement from high to low and down the valley - ice does, therefore, flow
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Definition What is a GLACIER ?
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lecture_17_glaciers - GLACIERS GEO 1115 Introduction to...

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