Geology 301 Part 3 - Ch.24 Glaciers I Glacier Ice A metamorphic rock a Snowflakes form on glaciers then transform in to"old snow grains-first stage

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Ch.24 Glaciers I. Glacier Ice : A metamorphic rock a. Snowflakes form on glaciers then transform in to “old snow,” grains—first stage of creating glacier ice b. Compacts to become “gneiss ice” black =ice devoid of bubbles, white=ice crowded with microscopic gas bubbles c. Crystals grow larger—ice crystals II. Profile of a glacier : Behavior of glacier ice a. Valley Glaciers/ Alpine Glacier i. In high elevation-- zone of net accumulation, snow covered ii. In Low elevation—zone of net ice wastage, ice net accumulation zone of ductile behavior zone of brittle behavior bed rock net wastage b. Monitor glacier movements by inserting flexible pipe and monitor its movement from slippage of the entire ice mass over the bed rock and internal deformation c. Temperature of glacier is exactly the freezing pt of the water d. “Cold” polar glacier—temperature below freezing because it was formed at a time where the climate was a lot colder. e. Bed of glacier is warmer because of geothermal heat III. Glacier Erosion and Deposition a. Ice in a polar glacier is frozen to the bedrock; ice motion in a temperate glacier may be lubricated by a thin zone of melted water. However, liquid water has been discovered in places at the base of the Antarctic ice sheet! Note that geothermal heat is brought up from below (preceding image). b. Erosion from ice sticking to bedrock and pulling them along with the flow c. Glacial Valley and its tributary valley forms hanging valleys with waterfalls d. Till is the sediments—moraine is the formation formed with till IV. Ice Ages a. Time scale: 10s to 100s of millions of years ancient ice ages, continental drift b. The Earth Today i. Ocean at north pole, continent at south pole ii. Ocean water currents are able to transport enormous quantities of heat energy 1. warm water can be transported north and south and cold water sinks a. helps the distribution of heat throughout the world iii. Characterization of World Climate 1. Icehouse Earth- Earth today a. Substantial ice around [Greenland, Iceland, Antarctica] 2. Greenhouse Earth a. warming 3. Snowball Earth
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a. Earth was entirely frozen b. Intensely cold and arid 4. Hothouse Earth a. Really hot b. Snowball Hothouse c. If a continental mass is located in a polar region, it will have an ice age V. Time Scale : 100s of thousands…. a. Modern Icehouse Earth i. Ice and Isotopes 1. H 2 O- isotopes a. 16 O- Light b. 17 O c. 18 O- Heavy 2. Meteoric water- characteristically light [deficient in heavy isotopes] Ice Sea level – basic starting point 3. Evaporation a. Light isotope evaporated but heavy remains 4. Precipitation a. Precipitation of Heavy while light remains a vapor VI. Climates earlier than a million years ago a. Take a core b. Analyze the foraminifera c. Result- shows the heavy- light isotopes of the water through CaCO 3 created by the foraminifera d. Heavier isotopes ice sheets expanded lower sea level colder climate e. Lighter Isotopes ice sheets reduced
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This note was uploaded on 04/24/2008 for the course GEO 301 taught by Professor Long during the Fall '07 term at University of Texas at Austin.

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Geology 301 Part 3 - Ch.24 Glaciers I Glacier Ice A metamorphic rock a Snowflakes form on glaciers then transform in to"old snow grains-first stage

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