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Antarctica Notes
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T/R 10-11:30 in Noble Hall (Annex) #1009
Rachel: Thurs
...
2 C on July 21,1983 near Vostok (Russian
Research Station)
Satellites suggest -94
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2 on July 31, 2015
World’s driest continent: on polar plateau < 50 mm (2 in
...
W: separated by Weddell Sea (beneath Atlantic ocean), Ross Sea (below New
Zealand) and Transantarctic Mountains
Weddell Sea: seas, ice shelves, mountains, subglacial lakes, ice-free lands, volcanic
island near Joinville Island, dry-valleys
Ross Sea: bordered on its west by E Antarctica & Transantarctic Mountains; less
hemmed in
Ice shelves (boundaries of Ross & Weddell Seas): floating ice extension of glaciers; Ice
Cliff seaward edge; “The Barrier” of early explorers- chunks of ice fall here so it’s
dangerous
Amery Ice Shelf: Prydz Bay- major indentation in E Antarctica Coastline; few locations in
E Antarctica of converging ice flow
Other seas: Bellingshausen, Amundsen, Scotia, *Southern Ocean

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Transantarctic Mountains: 3500km long; separate E from W Antarctica; important
geologic boundary; hand model (shape of left hand when put in a thumbs up)
Ellsworth Mountains: highest mountains in Antarctica- Vinson Massif (4892m, ~16080 ft);
base of Antarctic Peninsula
Major subglacial lakes: 145+ identified thus far
Lake Vostok is largest (14000 km^2)
Lake Whillans: 3931 diff specifies- some break down minerals for energy
Ice free lands: about 2% of Antarctica is ice free; found along coasts and mountainous
areas (dry valleys and nanutuks); geothermally heated
Dry valleys: cold wind on polar plateau flows downhill (cold air denser than warm air so
sinks) & removes potential snow/ice/precipitation
Latitude: earth’s tilt results in unequal sunlight distribution- long time period w/o sunlight
(Antarctic Circle is 66 33’ 44”)
Land: Continental effect makes Antarctica cold
Isolation from ocean currents: circumpolar ocean makes Antarctica cold

Subantarctic islands: between 46-60 degrees S
Important role in Antarctica- biological refugia; history of exploration
True “subantarctic islands”: S of the Polar Front; many tied due to bio or history of
exploration; vegetation include mosses to small trees, King of Penguins
Ex: True- S Shetlands, S Georgia (grass & exposed rock; more N), S Sandwich, Peters
Island, Heard and McDonald, Balleny Islands; Associated- Iles Kerguelen, Marion and
Prince Edward Island, Marquarie Island
Research bases- int’l effort
Ships & aircrafts
Antarctic summer is our winter
Largest research station in Antarctica by footprint and # of people: McMurdo
Over 40 permanent stations (always there, footprint never changes, year round staff)
About 2000 scientists & support staff every year
-McMurdo can have up to 1500 people during summer
Tourists
Main U
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stations: McMurdo, Amundsen-Scott S Pole & Palmer
Other countries have stations too: France, Italy, Germany, Spain, Brazil, Russia,
Ukraine, Uruguay, Chile, Argentina, S Korea, Japan, China, New Zealand, Australia,S
Africa, India, etc
Ships: USA (USAP-NSF)- Nathaniel B
...
25-2 degrees C, salinities 34
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72; flows north at depth
Antarctic Intermediate Water: forms just north of ACC in Antarctic Polar Front Zone;
most widespread intermediate water in world’s oceans; 2-4 degrees C and 34
...
Coastal Current: divergence upwelling- one of most
productive regions in open ocean in world → marine life
Earth’s energy mostly comes from sun: small fraction from earth’s interior- 150 mill km
away
Due to earth’s tilt, earth energy unbalanced: directness of sunlight; tropics- equal amount
of energy all year and poles- 6 months all, 6 months none
Warmer in Antarctica in N American winter

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Albedo: reflecting solar energy- highest w/white; 80% energy coming to Antarctica
reflected back
Thin gases surround earth
N2: 78%, O2: 21%, Argon: 0
...
04%, H2O: 0-4%
99% by mass within 30km of Earth’s surface
Climb a mountain & gain elevation it gets colder but heat rises & closer to sun as climb
mountain???
Earth’s layers (closest to farthest): troposphere → stratosphere → mesosphere →
thermosphere → exosphere
Troposphere: 0-11km, warmed by contact w/Earth, decreasing temp w/height
Stratosphere: separated from troposphere by tropopause,11-50km, stable temp then
increasing temp w/height due to ozone (O3) absorbing UV radiation
Mesosphere: 85-90km, separated from stratosphere by straopose, 99
...
oceanic) → mantle → outer core → inner core
Continental Drift: 1915 Alfred Wegener (German)
Pangea- S portion known as Gondwanaland (Antarctica, Africa, S American, India &
Australia)
Largely criticized for lack of a mechanism to drive it
Evidence for Continental Drift: fossils in Antarctica
Plate tectonics: unifying theory of geology, developed in 1960s w/some earlier
components
See plate structure thru several key observation related to distribution of topography,
ocean ages, earthquakes, volcanism
Topography: particularly the oceans
Age of ocean floor: older towards edge and vice versa
Antarctica: one plate- stable part of continent (Craton, E Antarctica)
Very few earthquakes & volcanoes in Antarctica (stable)
N & S America not as stable
Divergent: seafloor spreading; generate new crust
Most oceans surrounding Antarctica- Bransfield Basin
W Antarctica underlain by a rift systems
Shoulders of rifts are often mountains
Continental rifting: crust breaks apart → rift valley → sometimes evolves into a new
ocean
W Antarctica moving away from E Antarctic Craton
North/northeasterly direction (approximately in direction of S Georgia Islands)
Convergent leads to subduction
Oceanic plate subducts beneath continental
Convergent: ocean-ocean, ocean-continent, continent-continent
Ocean-continent: Andes, S America, S Shetland Islands
Ocean-ocean: Scotia Arc
Continent-continent: Himalayas; not ongoing in Antarctica
Transform boundary: 2 plates slide past each other; large scale version of a strike slip
fault (San Andreas Fault)
Also along some ocean plate- offsetting midocean ridges

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Subtle variation in gravity due to differences in rock densities
Measurements tell about underlying structure (faults, plates, etc) of Earth- sometimes
follows topography & many times can see structure beneath ground or ice
Hand measurements, ship, airplane
Several small blocks or “microplates” comprise W Antarctic
Sediment of continental crust (usually in contient interior) that’s been tectonically stable
for a long time (billion years or longer)- E Antarctica
Accretionary wedge: generally wedge-shaped mass of deformed sediment at a
subduction zone formed by transferring material from descending plate into framework of
overlying plate- forms at convergent boundaries
Subduction zone: area between sinking oceanic & an overriding plate
Subduction: oceanic plate sinks beneath overriding plate
Hot spots: anomalous region of volcanic activity that appear to remain stationary
beneath moving plates

Stress: force per unit area
Earth can behave as:
Elastic: stress removed, earth springs back (like rubber band)
Plastic: stress removed, earth keeps new shape (like silly putty)- folding
Brittle: breaks- faulting
Strain: deformation produced by stress
Geologic structure: any geologic feature produced by rock deformation
Fault: fracture in a rock along which one side has moved relative to the other side
Types: normal, reverse & strike-slip
Movement along these faults causes earthquakes
Horsts & grabens: landscape formed by faulting
Reverse: left side higher than right; normal: right side higher than left; strike-slip: more
perpendicular
Horsts & grabens:
Rifting
Lots of normal faults
Blocks of the earth- some “move up” (Horst- German for heap); some “go down”
(Graben- German for ditch)
Basin and Range (USA-Nevada)- example of ^
Antarctic: W Antarctic Rift System but buried by ice- example of ^
Fold: bend in rock
Generally found in zones of compression
Converging plate boundaries
Anticline fold: upward arched fold w/oldest rocks in center
Syncline fold: downward arched fold w/youngest rocks in center
Hanging block goes up relative to footblock w/convergent boundary
Hanging block goes down relative to footblock w/divergent boundary

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Rocks: atoms → elements → minerals → rocks
88 naturally occurring elements
98% is 8 elements: O, Si, Al, Fe, Ca, Na, K, Mg
Minerals: building blocks of rocks
Naturally occurring, inorganic solid w/a known chemical composition & a crystalline
structure
Crystalline: any substance whose atoms are arranged in a regular, periodically repeated
pattern (crystalline structure)
Minerals
Crystal habit: shape of mineral crystal & aggregate growth
Cleavage: tendency to break along flat surfaces
Fracture: manner it breaks other than along planes of cleavage
Hardness
Specific gravity: weight relative to equal volume of water
Color
Streak: color of fine powder of mineral
Luster: manner in which mineral reflects light
Mohs hardness scale: relative hardness, common minerals

Minerals on Moh’s Scale of Hardness: quartz, olivine, orthoclase, pyroxene, plagioclase
Geological map; ice, exposed rock, ice shelf (ex: Ross)
Igneous: rock that solidified from magma
Sedimentary: rock formed by accumulation & cementation of mineral grains by wind,
water or ice transported to site of deposition or by chemical precipitation at site under
normal surface conditions
Metamorphic: rock whose original mineralogy, texture or composition changed by effects
of pressure, temp, or gain/loss of chemical components
Rock cycle: sequence of events in which rocks are formed, destroyed, altered or
reformed by geological processes
Igneous rocks: 3 processes “melt’ asthenosphere
1
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Decreasing pressure
3
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Spreading centers- new oceanic crust formed
2
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Mantle plumes (hot spots)
Types of igneous rocks based on where it formed- controls its texture (nature, size &
shape of crystals)
Extrusive: cools at earth’s surface, fine texture- volcanoes
Intrusive: cools within Earth, coarse texture
Also classify them on their chemical composition

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Intrusive: granite (igneous), diorite, gabbro
Extrusive: rhyolite (igneous), andesite, basalt
Island arc plate subduction → plate divergence → hot-spot volcanism → continental
plate subduction- form igneous rocks at convergent & divergent boundaries
● Magmatic differentiation: variety of minerals crystallize from a single homogeneous
magma at diff temps; as minerals crystalize, chemical composition of magma changes
● Bowen’s Reaction Series: order in which minerals form from a melt dependent on temp
Olivine → pyroxene → amphibole → biotite
Igneous intrusions
● Pluton: large igneous bodies formed at depth in crust
● Batholiths: largest >100 km^2
● Stocks: <100 km^2
● Laccolith
● Sills & Dikes: tabular and either concordant or discordant w/host rock
● Sill: follow bedding, concordant, separates mountain range horizontally
● Dike: cuts across bedding, discordant, perpendicular to sedimentary layers
● Volcanoes around Antarctica- not all are active
● West Antarctic Rift
-possible hot spot- Mount Erebus
-other places along TAM & W Antarctic Rift
● S Shetland Islands
-subduction
-mid-ocean spreading (Bransfield Basin)
● Peter I Island- oceanic hotspot
● Buckle Island- mid-ocean ridge
● Volcanic activity depends on silica, water & gas content
● Effusive flows: low silica, flows downhill
● Pyroclastic: explosive, material ejected thru air
Types of volcanoes
● Stratovolcano (composite cone)- Mount Erebus: alternative pyroclastic & lava flows,
voent, rhyolite & andesite
● Shield Volcano- Peter I Island: lava flows, not so violent, basalt
● Cinder Cone: pyroclastic material, small, ejecta, basalt
1/31
Stratovolcano
● Mt
...
Sidley: highest volcano in Antarctica; 4285 m
● Caldera: large cauldron-like depression that forms following evacuation of a magma
chamber/reservoir; large circular depression created by explosive volcanic eruption
-magma erupts from bottom of earth’s surface & erupts and then rock collapses in
circular shape when magma gets sucked back down
-Deception Island, South Sandwich Islands

● Fumeral: gas vents (pipe where gas escapes from earth’s surface)
Shield volcano
● Shield-shaped
● Usually basaltic in composition
● Broad, low angle slope
● Hawaii-Mauna Loa
● Less violent
● Peter Island
● Subglacial volcanism
Sub-ice volcanism
● Flat-topped volcanoes
Metamorphic rock: rock whose original mineralogy, texture or composition has been changed by
effects of pressure, temp or gain/loss of chemical components
● Metamorphism: elevated temp & changes in other environmental conditions transform
rocks & minerals (increasing temp, increasing pressure, changing chemical composition)
Metamorphic changes:
● Textual changes- grain shape, size
● Mineral changes: elements recombine to form diff minerals
● Deformation: foliation- parallel alignment of micas & other minerals to make
metamorphic layering
● Slaty cleavage: parallel fractures along foliation planes
Site of metamorphism
● Contact: along magma intrusions, little to no deformation
● Burial: deep burial in sedimentary basins, no deformation
● Regional: due to tectonic processes, places like subduction zones; most widespread,
covers large areas
● Increasing metamorphic grade: slate → phyllite → schist → gneiss
● Increasing temp & pressure= metamorphic grade increases; higher metamorphic grade=
more changed rock will be from original form
● Metamorphic facies: way we characterize faces of rock
● Metamorphic rocks of Antarctic peninsula: generally see changes over large areas;
zones of similar temp & pressure conditions
Sedimentary rocks
● Rock formed by accumulation & cementation of mineral grains by wind, water or ice
transported to site of deposition or by chemical precipitation at site under normal surface
conditions
● Major components: weathering & erosion
Weathering: in situ decomposition of rocks & minerals at earth’s surface
● Forms soil (almost no soil in Antarctica)
● Rates relatively slow in cold & dry settings
● More physical rather than chemical weathering
● Erosion: transportation of weathered materials by wind, water or ice (ice really important
in Antarctica)

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Lithification: processes that convert loose sediment to hard rock
-compaction: weight compacts sediments resulting in a loss of pore space
-cementation: dissolved minerals precipitate in pore spaces w/in rock
Types of sedimentary rocks
● Clastic: composed of fragments of weathered rocks- sandstone, shale, conglomerate
● Chemical/biochemical: precipitation of minerals from a solution- carbonate (limestone),
gypsum, rock salt
● Carbonaceous: soft tissues of organisms- coal & oil
● Structures formed during or shortly after deposition tell about processes transporting
sediment that became rock
● Common structures: ripples, cross-bedding, mud cracks, grading, flutes
2/2
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Midterm: Tues
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7; big red scantron; #2 pencils; student ID; SG online; review quiz
Relative geological time:
-Original horizontality: sediments usually accumulate as horizontal layers
-Superposition: layers on bottom usually older than layers on top
-Cross-cutting relationships: a rock must first form before it can be cross cut by
something else
● Absolute geological time: radiometric dating
● Original horizontality: sediments were originally horizontal! (ex: Bryce Canyon in Zion
Park)
● Superposition: oldest layers are deposited first (youngest on top, oldest on bottom)
● Cross-cutting: a layer must be older than the layer dissecting it
● Unconformities: an interruption in deposition, usually of a long duration
Angular unconformity, nonconformity, disconformity
● Disconformity: Superposition → erosion event which removed sediment above it → time
is missing
● Angular unconformity: Original horizontality → layers tilted → erosion event → gap in
time → deposited sediment layers on top
● Only difference between ^ is that layers on bottom are tilted on angular unconformity
● Nonconformity: doesn’t conform to typical sedimentary cross section
Faunal succession
● Fossils: remains & other traces of prehistoric life
● Fossil organisms succeeded each other thru time in a definite & recognizable order and
that relative age of rocks can therefore be recognized based on their fossil content
● Index fossil: indicates age of rocks containing it
Review for Midterm
● ACC is same as West Wind Drift (clockwise); keeps Antarctica cold
● Antarctic Coastal Current is same as East Wind Drift (counterclockwise)
Igneous rocks
● Felsic: high silica, iron & magnesium poor- colder temp

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Ultramafic: low silica and low sodium and potassium- very dark, higher temp, crystallizes
first bc hot
Earth’s core is iron & nickel so iron is most common element on earth
Most common element in crust is silica & oxygen
[broad concepts & definitions]
West Antarctic Ice Sheet → Ronne and Ross Ice Shelf → Transantarctic Mountains →
East Antarctic Ice Sheet → Law Dome
West Antarctic Ice Sheet sitting on water, lower elevation, more susceptible to temp
changes & interacting w/ocean but less devastating effects than E Antarctic
Oceanic more dense than continental so subducts beneath continental at convergent
boundary
Don't need to know examples of boundaries, just principle
Concordant: sills run with bedding plane (parallel)
Discordant: Igneous magma forces its way up thru sedimentary layers; sometimes runs
perpendicular (cross-cuts)
Intrusive: large crystals means it cools slowly, under earth
Extrusive: cool quickly, small crystals
Don’t have to know name of seas and islands around Antarctica

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Geologic time: Precambrian- billion (Earth is cooling) → Phanerozoic- thousand of
millions (crust forms) → Cenozoic- hundreds of millions → Quaternary- tens of millions
● Lucy ~3
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9-0
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S
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S
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6 billion years old
● Oldest rocks in Antarctica: 4 billion years old
-near Enderby Land (NE Antarctica- under Africa)
-Mark the Napier Orogeny

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2/14
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Rest of E Antarctica craton assmedlbed by about 1 billion years ago by a series of ~6
orogenies
After Pangea, took ~175 Mya to move continents from Pangea to where they are today
Lots of crust subducted and additional orogenies
Small passages of open ocean between continents
Opening & closing thought to control global ocean circulation changes
Important Antarctic Gateways: Drakes Passage
-Antarctica & S America
-opened 41 Mya
-Atlantic & Pacific were separated
-Antarctic MUCH warmer (no ice captured)
-started ACC
Between Antarctica & Australia (separation ~30 Mya)
Glaciation: interval of time(thousand of years) within an ice age that’s marked by colder
temps and glacier advances
Throughout most of Gondwana (500 Mya) supercontinent has around w/respect to the
south pole
2 major Phanerozoic glaciations
-late Paleozoic (Carboniferous-Permian) 260-420 Mya
-Late Cenozoic (Oligocene+) 30 Mya

Geologic time: come over some day maybe play poker two jacks call
Sort of invasive species in Antarctica but not many
As late as mid-late Cretaceous (~85 Ma)Antarctica has had flowering plants in a
subtropical climate
-Summer temps average 20-24 C (68-76 F)
● Paleocene (~60 Ma)
-starts to cool, gradual loss of warm plants
● Late Paleocene (~50 Ma)
-cooled to average of 13 C
-strong seasonality (25 C summer, 2 C winter)
-like SF
● Eocene (~40 Ma)
-cool marine maritime climate (10 C)
-plant community dominated by Nothofagus
-like New England coast
Eocene/Oligocene Boundary
● Glaciers take over
● Drop in oxygen isotope records
● A few “refugia” still exist & ice sheets were largely “temperate”
● Experienced periods of waxing & waning
Miocene and Pliocene

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Tundra-type vegetation hangs on in most of Antarctica until middle Miocene (~13 Ma)
-hold on a little longer in Antarctic Peninsula (~12 Ma)
● By 14 Ma, East Antarctic Ice Sheet permanent
-prior to that it looks like it came and went with Milankovitch cyclicity
● Pliocene-Pleistocene
-no real plants
-relatively warm period during Pliocene in which West Antarctic Ice Sheet may have
been reduced greatly
-after 3
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7%, surface
water: 0
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9%
● Surface water- Swamps: 11%, lakes: 87%, rivers: 2%
● Oceans: most water and most evaporation
-88% of all evaporation from ocean
-79% returns to ocean as precipitation (rains)
-57% precipitation on land originated from evaporation over land
Conversion of snow to glacial ice:
● As snow buries, covers to granular ice, then firn, then glacier ice
● Loss of trapped air
● Glacier: massive, long-lasting, moving mass of compacted snow ice
● Ice sheet: glacier covering more than 50000 km^2
● Ice cap: continental glacier covering less than 50000 km^2
● Glaciers from small to large
● Antarctic Ice Sheet: 13 mill km^2 (1
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1km of sediment core (a lot)
2/16
Mass balance of glaciers (zones)
● Accumulation: mass or quantity of something that’s been gradually gathered or acquired
● Ablation: removing snow & ice by melting or evaporation typically from a glacier or
iceberg
● Zone of accumulation: more snow & ice falls in winter than melts in summer
● Zone of ablation: more snow & ice melts in summer than falls in winter
● Melting: solid to liquid
● Sublimation: solid to gas
-like dry ice but happens to normal ice too
-atmosphere cold & dry
● Calving (physical breakdown)
-icebergs breaking off into ocean/lake
-dominant form of ablation in Antarctica

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Birth of an iceberg
-”Chasing Ice” video from Greenland
Parts of a glacier
● Terminus/snout: end of glacier
-point where flow of glacier can’t keep balance w/ablation
-glacier termini are great tracers of climate change
● Snow line: boundary between permanent snow and seasonal snow
-may change from year to year depending on weather
Crevasses
● Zones of tension vs compression
● Mark topography of underlying bed
● Ice still moves even if amount of ablation = amount of accumulation
Internal glacial mechanics
● Glaciers are like conveyor belts (or tank treads)
● Terms advance & retreat -only apply to terminus/snout
● If a glacier is in “equilibrium,” it neither advances nor retreats but ice is still moving →
eroding bedrock
Types of glaciers
● Alpine: in mountain ranges, high on mountain side, in bowls & cirques
● Continental: extremely large & broad (same as ice sheet)
● Rocky/dirty: ice bound rock or rock on ice
● Tidewater: glaciers that terminate at the ocean
Icebergs
● Calve from front of a glacier
● Drift with wind/current
● Tidewater Glaciers- calve from glaciers that terminate in the sea
2/21
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Cirque glacier (alpine): small glacier located in a cirque; doesn’t extend beyond edge of
cirque; leis in cirque at head of glacier
● Valley glacier: alpine glacier flowing in a valley; valley walls restrict glacier flow; glaciers
start in cirques and extend down-valley from cirques
Ice shelf
● A floating extension of land ice
● Antarctica surrounded by ice shelves
● Difference between sea ice & ice shelves is that the former is free-floating
-sea freezes & unfreezes each year whereas ice shelves are firmly attached to the land
● Major Antarctic Ice Shelves: Ross, Ronne, Larsen, Amery
● Ice shelf: a sheet of very thick ice with a gentle or undulating surface which is attached to
the land along one side but most of which is afloat & bunded on seaward side by a steep
ice cliff rising up to several hundred meters above sea level
-Fed by outlet glaciers; probably “buffer” outlet glaciers
Ice streams

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A current of ice in an ice sheet or ice cap which flows more rapidly than surrounding ice
Not constrained by exposed rock
Discharges most of ice & sediment from ice sheets
Flows orders of magnitude faster than surrounding ice
Thicker ice = faster velocity
Thicker ice = greater basal temp = basal melting
Meltwater also flows towards & accumulates in topographic lows
These factors encourage basal sliding
Positive feedback system with enhanced flow increasing temp and basal lubrication
which increases flow, leads to ice stream development in topographic corridors
● Antarctic Ice Sheet currently discharges 90% of ice & sediment thru ice streams
● Essentially fast flowing glaciers
● Antarctic Ice Stream ed by complex turbinates that extend up to 1000 km into intero of
ice sheet
Ice falls
● Ice equivalent of a waterfall
● Ice flows over a drop-off, glacier breaks apart, often forming transverse crevasses
● Reforms at base of drop-off
Ogives
● Alternating bands of light & dark ice that form a series of ridges & swales at base of
some ice falls
● Appear as “waves” below ice fall
● Shows seasonality of ice flow
-summer (trough): ablation, exposing cracks which fill with rock & debris
-winter (peak): surface covered in snow, protecting it from weathering & creating the light
band
Abrasion
● Mechanical scraping a rock surface by friction between rocks & moving particles during
their transport
● Resulting features:
-striation/groover: shallow to deep scratches in bedrock (parallel to flow direction)
-polished surfaces: relatively recent glacial activity or protected with debris
● Chattermarks: depressions carved from removing of rock flakes
-crescent-shaped marks caused when glacial ice drags rocks & debris underneath it
Plucking
● Glacier freezing to bed, moves pulls fragments away
● Facilitated by fractures in bedrock & basal melting
● Main mechanism for entrainment of debris used in glacial abrasion
● Rocks entrained within the ice is doing the abrasion (ice hardness ~ 1
...
3m to 6-9m globally)
Solar output changes
-Bond Cycles: ~3 kyr cycles
-Sunspot Cycles: ~11 yr (more sunspots, more solar energy released)
● Early and Mid-Holocene: warmer in Antarctica
Little Ice Age: best expressed in S Shetland Islands
● Between 1300-1870 during which Europe & N America were subjected to much colder
winters than during 20th century
● Overall Antarctica was cooler & stormier during LIA
● Antarctic surface temps ~2 C colder
El Nino
● Periods of warmer ocean temps along Equatorian coast; brings changes in Antarctic
weather too
● High pressure over Amundsen & Bellingshausen Seas
-reduced sea ice & warmer conditions
● Weddell Sea: colder & more ice
Drivers of climate change
● Solar output
-Bond cycles, sunspot cycles
-Milankovitch cycles
● Ocean-current changes
-diff temporal scales (gateways to seasonal)
-casing warming across parts of Antarctica
● Wind pattern changes
-Circum-Antarctic winds have increased 15-20% over last 30 years
● Greenhouse gases: CO2
● Increasing CO2 in atmosphere
● Ice cores (taken in Antarctica): temp, dust, sea salts, other gases (N2), pollutants,
meteor impacts, volcanic eruptions, climate changes
Carbon-14 cycle
● Radiation bombarding Earth (incoming radiation)
● Formed in upper atmosphere
● Plants & trees absorb CO2- incorporate C-14 into living tissues
● Animals eat plants- ingesting small amount of C-14
● Plant absorbs CO2 → dies → turned into coal → burn coal -> back in upper atmosphere
● Oceans remove 26% of CO2 emissions
-dampens atmospheric effect
Increases acidity of oceans (30% increase in last 250 years)
Volcanic eruptions
● Cools Earth → put ash & aerosol into stratosphere- reflect radiation back to space
● Mount Pinatubo (0
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5C cooling)

3/2
Ocean Acidification w/Rob Dunbar- Video
● 4 natural causes of climate change?
-air sea interaction, ocean circulation, volcanic aerosol & dust, solar output
● 3 ways humans affect global climate?
-change surface of land, inject aerosols into atmosphere, trace gases (meth, sulfur, etc)
● Where did scientist drill for records?
-Ross Sea Ice Shelf, in sea bed; S of Antarctic Circle
● Did they collect ice or sediment cores?
-sediment
● How many alterations did they discover between open water & ice covered water?
● How many years did this occur?
● Amount of sea level change each time?
● How many meters do scientists expect current sea levels to rise by end of century?
2-3m
● Air temps warming in many parts of Antarctica
-W Antarctica: 0
...
23 C per decade
Antarctic Peninsula: 0
...
31 C per decade
● Antarctic Peninsula one of the fastest warming places on Earth
-global avg: 0
...
03 C
● W Antarctic Ice Sheet contributing to sea-level rise
● Record reveals a linear increase in annual temp from 1958-2010 by 2
...
2 C
● Central W Antarctica one of fastest warming regions globally
● Statically significant warming during Australia summer (Dec-Jan), peak of melting
season
● Southern Ocean: +1 C over last 80 years down to 3000 m
West Antarctica- Pine Island Glacier (PIG)
● “Weak underbelly of Antarctic Ice Sheet”
● Responsible for about 25% of Antarctica's ice loss
● Fastest melting glacier in Antarctica
● Mass losses from PIG and Thwaites Glacier dominate Antarctic ICe Sheet ice losses
● Mass loss from this basin doubled from 1996-2006 and it’s largest ice loss in Antarctica
● Other observations of change: temp, wind, sea-ice, biology, glaciers, ice shelves,
sea-level rise
Changing winds
● Circum-Antarctic Winds increased by 15-20% in last 20 years
-driven by warmer sea surface temps in winter
-driven by more storms during summer
● Impact ocean mixing
-more mixing, less CO2 uptake by oceans
Sea ice trends

●

Spatial differences
-increasing: Ross Sea; slightly: Weddell and Indian Ocean sector
-decreasing: Amundsen and Bellingshausen Seas
● Spatial variation is suggestive of changes in atmospheric circulation
Biological changes
● Krill decreasing
-due to changing phytoplankton communities
-less diatoms (diatom blooms associated w/sea-ice)
-more cryptophytes- not edible by krill
● Salp increasing
● Largely linked to changes/decreases in sea ice
● Penguins
-more difficult to interpret
-related to sea-ice extent when penguin hatches
*ore sea-ice bad, less sea-ice good
-also related to krill stocks
*more sea-ice good, less sea-ice bad
● Krill populations play a critical role in determining # of penguins
-both “ice-loving” and “ice-hating” penguins
-Chinstrap and Adelie
Glaciers
● 85% of 244 tidewater glacier surveyed retreated in Antarctic Peninsula over last 50 years
● Ice Shelves rapidly retreating due to
-increased temp- surface melt water fraction
-basal melting from increased ocean temps
● Most ice shelves in Antarctic Peninsula are retreating
Satellite Measurements of Mass Change
● GRACE: Gravity, Recovery And Climate Experiment
Implications for sea-level rise
● Melting ice
-sea ice: no changes in sea level
-ice shelves: no changes in sea level
-but buttressing effect lost → glaciers speed up behind- contributes to sea level rise
-ice Sheet mass: increases sea level
Rising sea level
● Global average
-1900-2009: 1
...
2 mm/yr satellite data
● Regional variations; look at elevation of sea surface
● Estimates vary
● 2 main sources
-Thermal Expansion of oceans
A
...
8+/-0
...
0
...
0
...
2 mm/yr
B
...
21+/-0
...
11 mm/yr, -0
...
3-0
...
S
...
-C
...
S
...
F
...
Erebus
● Used ponies, tried cards (didn’t work)
● Pioneered Beardmore Glacier to S Pole
● Southern march reached 88 degrees 23’ S, a new Farthest South record 97 mi from Pole
● Northern Party reached location of S Magnetic Pole (not geographic, like he wanted)
Amundsen- Bay of Whales (1910-12, ​Fram​)
● Race to S Pole
● Very diff tact
-small, light swift, learned from N expeditions
-flawless execution
-great equipment
-food hosen well
● Discovered NW Passage
● Originally planned to do N Pole but someone made it there first to headed to S Pole
instead
● Used dogs
● First season ladi Depots along the way- 7500 lbs of supplies
● Wintered over there (stated Sept
...
19, 1911)
● Named several mountains- Queen Maud Mountains (part of TAM)

● Made it to pole Dec
...
S
...
1938-Jan
...
4,1957
● Int’l Council of Scientific Unions recognize need to continue collaborate Antarctic
Science
-SCOR, COSPAR, SCAR
SCAR
● Continue coordinate of scientific activity on Antarctica after IGY
● Last one to continue
● 39 member countries & 9 scientific unions today
● Advise Antarctic Treaty
● Confirm Antarctic Peninsula Warming in E Antarctica
● Mass balance of Antarctic Ice Sheets
● Determined that during Larsen Ice Shelf Collapse, westerly winds brought warmer air
across Antarctic Peninsula
● Established plans for exploring Subglacial Antarctic Lakes
● Document distribution, abundance & long-term trends in Antarctic and Subantarctic
seabirds
Operation Highjump (1946)
●
●

Post WWII as part of demobilization of military - US
13 ships, 23 aircraft, 4700 personnel

●

Mapped parts of Antarctica – Amundsen sector, Ross Ice Shelf, and discovery of the
Bunger Hills
● Rewards not commiserate with effort
● -Largely a military exercise – training of troops, etc
...
S
...
4 million km^2
● Starting to shrink

3/16
Review
● Less electrical orbit = less eccentricity (Milankovitch)
● Obliquity (Earth’s tilt): how steep tilt it
● Precession: earth spins like a top- affects where in Earth’s orbit the summer is; summer
farther away in orbit = cooler summer and vice versa
● Ross Ice Shelf advance/retreated 35 times in last 4 million years
● Oceanic crusts are denser (even if they’re younger) so subduct under continental
● 60-70m extra sea-level if ice melted
● Determine plate boundaries from earthquakes & volcanoes
● Ocean crust is denser than continental crust; continental crust thicker than oceanic
● 125 questions



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