Sum11.208.IceAgesFloods - Basic Glacier Types Valley...

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Unformatted text preview: Basic Glacier Types Valley Glaciers (South Cascade Glacier) Ice Ages and the Missoula Floods Ice Sheets (Greenland) H-2 Anatomy of a Glacier Climate Since the Cenozoic When it gets colder or wetter glaciers get bigger Tukwilla Fm Vashon Fm Blakeley Fm How do we know that we have been in an Ice Age for 2 Myrs? 1. Glacial Erosion Evidence of: 1. Glacial Erosion 2. Glacial Sediments 3. Glacial Landforms Mt. Stuart U-Shaped Valleys Chester Morris Reservoir The Fjords of Washington Drumlins / Streamlined Hills Striations LIDAR Image 2. “Glacial Drift” (Sediments) 3. Glacial Landforms Moraine Glacial Erratic Baird Glacier, Alaska Glacial Till and Moraines Looking East over North Bend Mt Si Snoqualmie Moraine Glacial Outwash: Sand and Gravel Glacial Erratics Wedgewood Erratic, Seattle Fantastic Erratic, Cougar Mtn Issaquah Gravel Pit Glacial Lake Deposits Kettle Lakes Larson Lake Phantom Lake Phantom Lake Larson Lake Lake Boren (map D Molenaar, 1987) H-1 North American Ice Sheets H-4 17,000 years ago Last Glacial Period (ca. 20,000 yrs) Puget Sound During the Ice Age Puget Sound Ice (A Modern Analogy - Columbia Glacier, AK) Austin Post (map D Molenaar, 1987) H-10 Sequence of Events Puget Sound Animation Discovery Park Till Till Outwash Outwash Lake clays Lake clays Pre-glacial deposits Pre-glacial deposits H-3 Seattle Area Shows Evidence for Several Glacial Advances Glacial Formations in Puget Sound H-2 Climate Since the Cenozoic H-3 Glacial Cycles Within an Ice Age Interglacial Period Glacial Period 2 Myrs Quaternary Ice Age Glacial Sediments in Puget Sound H-4 Scablands From Space Missoula Floods (AKA Spokane Floods, Bretz Floods, Ice Age Floods…) Ice Dams Glacial Lake Missoula Giant Ripple Marks Dry Falls H-5 Columbia Gorge “Ponding” of the Floods H-4 Lake Allison to the Sea Evidence for over 40 floods! “Rhythmites” H-5 Varves in Glacial Lake Columbia Glacial Lake Bonneville 20-50 yrs between floods Hell’s Canyon Into the Geologic Future… Next 10 Myrs Into the Geologic Future… Cascades “Shut Off” After 10 Myrs ...
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