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Geology of the Hawaiian IslandsGeology of the Hawaiian IslandsClass 25Class 25
13 April 200413 April 2004
Any Questions?Any Questions? Earth Systems Today CDEarth Systems Today CDClick on “Weather and Climate”Click on “Weather and Climate”Look at the sections onLook at the sections on
El NiEl NiññooOzone HoleOzone Hole
GlaciersGlaciers
Why do we Why do we care?care?
They help They help control control global global climateclimate
GlacierGlacier
Body of ice, snow, Body of ice, snow, firnfirn, and , and meltwatermeltwaterlying wholly or mostly on land showing lying wholly or mostly on land showing evidence of present or former motionevidence of present or former motion
Glaciers form where more snow Glaciers form where more snow accumulates in winter than melts in accumulates in winter than melts in summer.summer.
Types of GlaciersTypes of Glaciers
alpine:alpine: restricted to mountainous systemsrestricted to mountainous systems
continentalcontinental: covers extremely large areas: covers extremely large areas
Antarctica: 12,500,000 kmAntarctica: 12,500,000 km22 up to 3 km up to 3 km thick, 80% of the ice on earth, 65% of thick, 80% of the ice on earth, 65% of the fresh waterthe fresh water
Greenland: 1,700,000 kmGreenland: 1,700,000 km22 3.2 km thick3.2 km thick
Sentinel Range, AntarcticaMorphological classificationMorphological classification
Valley glacier Valley glacier
Ice cap glacierIce cap glacier
Ice sheet glacierIce sheet glacier
Greenland Greenland Ice CapIce Cap
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Antarctic Antarctic Ice SheetIce Sheet
Glacial BudgetGlacial Budget(Net Loss)
Calving Glacier,Glacier
Bay,Alaska
Stages of Antarctic Stages of Antarctic Ice Shelf RetreatIce Shelf Retreat
Ice Flow in a Ice Flow in a Continental Continental
GlacierGlacier
Glacial erosionGlacial erosionVV--shaped valley shaped valley vs.vs. UU--shapedshaped
hanging valleyshanging valleys
Creation of Creation of Hanging Hanging
Valleys and Valleys and Associated Associated Waterfalls, Waterfalls, Before and Before and
After After GlaciationGlaciation
U-shaped Glacial Valley, Glacier National Park,
Montana
Steve Kaufman/DRK
Glacial Polish, Striations, and
Grooves, Glacier Bay National
Park,Alaska
Carr Clifton
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Stephen J. Krasemann/DRK Photo
LateralMoraines
MedialMoraines
Pleistocene continental Pleistocene continental glaciationglaciationGreat ice sheets extended into temperateGreat ice sheets extended into temperateregions 4 times in the past:regions 4 times in the past:
WisconsinWisconsin 0.20 0.20 –– 0.018 Ma0.018 Ma
IllinoianIllinoian 0.55 0.55 –– 0.40 Ma0.40 Ma
KansanKansan 1.40 1.40 –– 0.95 Ma0.95 Ma
NebraskanNebraskan 2.00 2.00 –– 1.75 Ma1.75 Ma
Northern Northern hemisphere hemisphere
during during the last the last
glacial ageglacial age
Ice cores from the Vostok Station,
Antarctica
Advances and retreats Advances and retreats of continental glaciersof continental glaciers
Worldwide and essentially Worldwide and essentially instantaneousinstantaneous
Implies Global climate controlImplies Global climate control
Oxygen isotopes and the record Oxygen isotopes and the record of global climate changeof global climate change
Ordinary Oxygen has atomic mass of Ordinary Oxygen has atomic mass of 16 (O16 (O--16)16)
OxygenOxygen--18 has 2 extra neutrons, so its 18 has 2 extra neutrons, so its atomic mass is 18 (Oatomic mass is 18 (O--18)18)
Oxygen isotopes and the record Oxygen isotopes and the record of global climate changeof global climate change
During glacial times, ODuring glacial times, O--16 is 16 is preferentially evaporated from the preferentially evaporated from the oceans because it is lighteroceans because it is lighter
OO--16 is then precipitated and 16 is then precipitated and “captured” by glaciers, leaving the “captured” by glaciers, leaving the oceans with a higher concentration of oceans with a higher concentration of OO--1818
Oxygen isotopes and the record Oxygen isotopes and the record of global climate changeof global climate change
Foraminifera are small animals in the Foraminifera are small animals in the oceans that secrete calcium carbonate oceans that secrete calcium carbonate shellsshells
During glacial times, the oxygen in their During glacial times, the oxygen in their shells is higher in Oshells is higher in O--18 than O18 than O--16 16
Isotopic record of changing ice volume over the Isotopic record of changing ice volume over the past 2 million years based on deeppast 2 million years based on deep--sea coressea cores
Fig. 12.32
Millions of Years Before Present
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Glaciers and Sea Level ChangesGlaciers and Sea Level Changes
Lots of water in glaciers: during last ice Lots of water in glaciers: during last ice age sea level lowered by ~130 mage sea level lowered by ~130 m
If all ice in glaciers today would melt, sea If all ice in glaciers today would melt, sea level would rise 65m: Major parts of level would rise 65m: Major parts of Florida, Egypt, Hong Kong, London, Florida, Egypt, Hong Kong, London, Houston would be floodedHouston would be flooded
What causes ice ages?What causes ice ages?Variations in Earth's orbitVariations in Earth's orbit
Changes in the atmosphereChanges in the atmosphere
Changes in circulation of sea waterChanges in circulation of sea water
Changing position/relief of the continentsChanging position/relief of the continents
No single one of these explains all ice No single one of these explains all ice ages ages –– must be some combination.must be some combination. Geometry of Earth’s
orbital variations and tilt
Global wind Global wind patternspatterns
Thermohaline Oceanic Circulation
Global Circulation Patterns Established
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Circulation is cut off High Mountains Change Atmospheric Circulation Patterns
The Hydrologic The Hydrologic CycleCycle
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Ozone is a molecule formed of 3 Oxygen atoms (O3) that forms a natural filter, absorbing the harmful rays of the sun.
Chlorofluorocarbons in the atmosphere are attacked by UV radiation
Chlorofluorocarbons in the atmosphere are attacked by UV radiation, liberating a chlorine atom
Chlorine combines with O atoms
Chlorine combines with O atoms to form ClO
ClO atoms then attack Ozone
ClO atoms then attack Ozone to liberate O2 into the atmosphere
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2 Ozone atoms are thus changed into 3 O2 atoms
The Problem:
O2 is transparent to harmful UV rays, so they pass through
Effect of greenhouse gases on incoming and outgoing radiation
The climate system
Atmospheric COAtmospheric CO22 measured at Mauna Loameasured at Mauna Loa
CO2FossilFuels
Increases in COIncreases in CO22 and use of fossil fueland use of fossil fuel
Historical Historical temperature temperature
changeschanges
Predicted increases in winter temperatures Predicted increases in winter temperatures with doubling of COwith doubling of CO22
Questions? Questions?
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ThursdayThursday
Last Web Class Last Web Class –– Kaua`iKaua`i and the NW and the NW Hawaiian IslandsHawaiian Islands
Don’t forget to do the last Virtual Field Don’t forget to do the last Virtual Field Trip and onTrip and on--line quizline quiz