Presentation on theme: " Began 2-3 mya Last glacial period ended 15,000 years ago Pleistocene epoch Ice covered 30% of Earth’s land Indirect effect of Ice Age glaciers:"— Presentation transcript:
Began 2-3 mya Last glacial period ended 15,000 years ago Pleistocene epoch Ice covered 30% of Earth’s land Indirect effect of Ice Age glaciers: Migration of animals and plants Rebounding upward of crust Worldwide change in sea level Climatic changes 1 Ice Age Figure 6.22: Max extent of ice during the Ice Age. Glacier Power, (3:34) Formation of Glaciers, (3:50)
Time of low temperatures Time of glacier advances Interglacial: warm periods within an ice age Currently: Holocene epoch interglacial Theory: current warm climate another 50,000 years Glacial periods named by geographic distribution Wisconsinian (26,000-13,000 ya) ice sheets to 45 N Ice sheets 3-4 km thick Isostatic rebound: reshapes land after ice removed Isostatic rebound: Illinoian (300,000-100,00 ya) Pre-Illinoian (2.5-0.5 mya) 2 Glacial Period Google Images, Gulkana glacier in Alaska
Core sample removed from ice sheet Contains ice formed over many years Provide more info than tree rings, sediment layers Ice properties, inclusions Ice Used to reconstruct temperature records Contain atmospheric composition Contains wind blown dust, ash, gas bubbles Contain radioactive substances Records: temp, ocean volume, atm chemistry and gas composition, volcanic eruptions, solar variability, forest fires Core ages: few years-800,000 years 3 Ice Cores Reading Ice Cores, (8:26 ) Google Images, Ice Cores
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