Glaciers: Denali National Park
Horn = the Matterhorn
Swiss Alps 200 Years Ago
Striations & Grooves
Striated & Polished “Pavement” Till - Sediment Type
Erratic = Rock from Distant Outcrops
“BFR”
Boulders in Northern Germany, Poland: Rock Types Whose Nearest Outcrops Are in Norway and Sweden; Erratic Boulders in PA, OH, NY Are from Outcrops in Canada
Explanations for Erratics, Striations, Grooves, etc.:
• Big Debate: early 1800s • Noah's Flood ? • Ice Berg Rafting ? – Drift
• Any Ideas? New Theory Developed in Early 1800s: • 1815: Swiss engineer hiking in Alps explained flood & ice-berg theories to “unlearned rabble”. • Peasant Laborer: striations, etc. created beneath glaciers today. Glaciers were once larger.
Louis Agassiz (a fishy scientist) at first = big opponent. • Agassiz: field work to disprove theory. • found Europe Was glaciated. • Biggest Advocate - 'Theory of Glaciation“ • Harvard,1848. • North America Was Glaciated.
Old Ice Great Sheets Ice Age
~
Laurentide Pleistocene Ice Sheet Epoch WVU By 1890s - Not One but FOUR Glaciations
• Wisconsin (last) • Illinoian • Kansan – Don’t write this down • Nebraskan (first) – Don’t write this down
1960s, 1970s: TENS of glaciations in the Pleistocene and Earlier
• "Little Ice Ages" in 10,000 yr since Pleistocene
• Many others in geologic history!
Oxygen Isotopes in Ice Cores
Record Global Wisconsin Ice Volume for 120,000 years Abrupt End of Wisconsin Glaciation
Interglacial = Holocene
Younger Dryas
Glacial = Pleistocene
What is a Glacier?
♦Mass of Ice ♣Derived from Snow ♥Lasts from Year to Year ♠Moves Due to Its Own Weight
Snow Xlizes in Air
Snow Converts to Firn in Time
Becoming Much More Dense Snow Firn Glaciers Move by Sliding and by Creep
Sliding Requires Film of Water at Bottom of Glacier
How Can a Film of Water Form at the Bottom of a Glacier?
Geothermal Heat All Glaciers Creep Like Silly- Putty
Polar Glaciers: Too Cold to Slide Temperature Summer Winter
Depth Frozen at Bed
Polar Glaciers: Too Cold to Slide (They Creep Very Slowly) Byrd Glacier Antarctica
Glacier Terms Cirque Arete Valley Fjord, or Fiord Piedmont Ice Cap Outwash
Find These: Arete, Horn, Cirque, Valley Glacier + + - - -
Mass Balance Nisqually Glacier, Mt. Rainier, WA
© Jason Bruggeman 2000 A.D.
Mass Balance http://www.normboynton.com/Wallpapr/wallglcr.htm
Emmonds Glacier, Mt. Rainier, WA Digital photo copyright Norm Boynton, 2000.
Moraine from ~ A.D. 1750 Glacier Covered by Debris
Emmonds Glacier, Mt. Rainier, WA Digital photo copyright Norm Boynton, 2000.
Emmons Glacier Extent ~ A.D. 1750, Accumulation Zone
Ablation Zone
Zones on Glacier in Canadian
Accumulation Rockies Zone
Ablation Zone
What is a Glacier?
♦Mass of Ice ♣Derived from Snow ♥Lasts from Year to Year ♠Moves Due to Its Own Weight Accumulation Zone
Ablation Zone
“Little Ice Age” in the French Alps
Same Glacier in the French Alps: Late 20th Century Moraine = Landform on Margins of Glacier
Lateral Moraine
Medial Moraine
End Moraine
Moraines, Alaska Surging Glaciers
Looped Moraines
Malaspina Piedmont Glacier, Alaska Medial Moraines
Vatnajokull
Vatnajokull, an Ice Cap
Volcano
Vatnajokull, Iceland Largest Glacier “in” Europe Ice Cap, Fiords in Patagonia (tip of South America)
Fiords or Fjords
Bear Glacier Calving Icebergs, Alaska Holgate Glacier, Alaska
“Small” Antarctic Iceberg
• Only 10-20 % Images not for web reproduction!meets the eye.
Digitally Enhanced Image
Extreme Ice Survey
http://www.extremeicesurvey.org/index.php/time_lapse/
http://www.extremeicesurvey.org/ Laurentide and other Ice Sheets
Indirect Effects of Glaciation
Isostacy Isostacy
Long-Term Changes in Sea Level – Pleistocene “Ice Age” 400-500 ft Lower
Ice-Age Climate = “Chilly” Ice Age Climate
Ice Age Climate
Great Lakes Product of Late Cenozoic Glaciation Source: NOAA http://www.glerl.noaa.gov/pr/ourlakes/background.html Lake Mon
Lake Tight Teays Depot
After: Hansen, 1995, Ohio Geological Survey Geofacts No. 10
Lake Monongahela Map http://www.dcnr.state.pa.us/topogeo/pub/pageolmag/pdfs/v32n1.pdf
Uplands >3000 ft
Full Glacial Pleistocene W.Va.!
Lowlands <3000 ft Migration of Species