BEACH NOMENCLATURE

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BEACH NOMENCLATURE
FORESHORE is the part of the beach that includes
the interval between the high and low tides
lines. BACKSHORE is the part of the beach
extending from the high tide line to the
vegetation or cliff face. BEACH FACE is the
steepest part of the foreshore zone. BERM is a
landward sloping mound of sediment on the beach
deposited by storms.
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BEACH NOMENCLATURE
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COASTAL DEPOSITIONAL LANDFORMS
SPIT
New Brunswick, Canada
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COASTAL DEPOSITIONAL LANDFORMS
HOOK
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COASTAL DEPOSITIONAL LANDFORMS
TOMBOLO
Popham Beach State Park, ME
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HUMAN INDUCED COASTAL DEPOSITION
BREAKWATERS
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HUMAN INDUCED COASTAL DEPOSITION
GROINS
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HUMAN INDUCED COASTAL DEPOSITION
JETTY OR JETTIES
Marina del Rey, CA
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DESERTS are regions that receive very little
rainfall, generally lt25 cm/yr (lt10 in/yr) and
are sparsely vegetated. DESERTS are
characterized by dryness, NOT sandiness. DESERTS
are not devoid of life.
This is the desert. Theres nothing out
here. Nothing. -N. Karavasiles Yuha Desert, CA
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Classification of DESERTS is based on
aridity. Use ARIDITY INDEX. Aridity index (AI) is
the ratio of annual evaporation to annual
precipitation. AI 1 indicates evaporation
precipitation Represents a humid climate AI
4 indicates four times as much evaporation
as precipitation Represents desert climate. AI
1.5-4 represents semi-arid climates.
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TYPES OF DESERTS
SUBTROPICAL DESERTS
Produced by atmospheric convection cells in
equatorial regions. Sahara Desert, Arabian
Desert
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TYPES OF DESERTS
RAIN SHADOW DESERTS
Produced on the leeward side of mountain
ranges. Cascades, Sierra Nevada, Rockies
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TYPES OF DESERTS
CONTINENTAL INTERIOR DESERTS
Exist because land mass is so large, the interior
is far from ocean moisture sources. Gobi
Desert
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TYPES OF DESERTS
DESERTS NEAR COLD OCEAN CURRENTS
Cold air from cold ocean currents move over
land. Air warms. Evaporates water from the land
surface. Atacama Desert in Chile
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TYPES OF DESERTS
POLAR DESERTS
Remain cold all year. Only cold, dry air
circulates in these regions. Greenland,
Antarctica
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WEATHERING IN DESERTS
Mostly mechanical weathering. Exfoliation Frost
wedging Salt crystallization Some chemical
weathering Chemical weathering produces DESERT
VARNISH. DESERT VARNISH is a coating of manganese
and iron oxides on rocks in deserts. Extremely
slow process
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WEATHERING IN DESERTS
DESERT VARNISH
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WATER IN DESERTS
WATER is the most dominant force of erosion in
deserts! Most desert erosion happens rapidly in
FLASH FLOOD events. These short lived desert
streams rapidly erode ARROYOS.
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WATER IN DESERTS
FLASH FLOOD
Before
After
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WATER IN DESERTS
ARROYOS
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WATER IN DESERTS
PEDIMENT
PEDIMENTS are gently sloping (lt5?) erosional
surface produced by erosion at the base of
mountains.
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WATER IN DESERTS
INSELBERG
INSELBERGS are final stage of the erosion of a
mountain. Result may be reduced to a
resistant, steep-sided bedrock knob.
Uluru (Ayers Rock), Australia
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STREAM DEPOSITON IN DESERTS
Generally produces ALLUVIAL FANS at the base
of mountains.
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STREAM DEPOSITON IN DESERTS
Water may also collect in desert basins as
temporary lakes. The lake may then evaporate
producing a PLAYA. PLAYAS are deposits of salts
precipitated as the lake water
evaporates. Deposits include BORAX (Sodium
borate or Na2B4O7.20H2O). 20 Mule Team Boraxo and
Death Valley Days Great Salt Lake/Dead Sea
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PLAYA
Death Valley, CA
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THE WORK OF WIND IN DESERTS
After water, wind is the second-most effective
force in the erosion of desert features. Wind is
produced by heat changes in deserts.
Ventifact
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THE WORK OF WIND IN DESERTS
EROSION BY WIND - DEFLATION
Most changes in deserts are due to movement of
particles. Occurs because there is very little
vegetation to hold soil or sediment in
place. Particles moved in deserts can then abrade
other rocks causing erosion.
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DESERT PAVEMENT
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SALTATION
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DUNE FORMATION
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Navajo Sandstone, UT
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LOESS
Is wind-blown silt-sized particles. Resembles
fine-grained lake mud. Accumulates downwind of
plentiful supplies of silt. Generally as glaciers
melt, rock flour is released. Rock flour is
silt-sized particles. These particles are
transported away from the glacier by water and
later deposited. Once deposited, it is moved
around by wind. Has accumulated to great
thickness in the American Midwest and in China.
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LOESS
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Dust Bowl, Kansas, 1935
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Nef Glacier, Patagonia, Chile Courtesy of Anna
Barensfeld
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Calving glacier in Greenland.
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Types of Glaciers
Continental Glaciers
Greenland - present
Ice sheets, gt50,000 km2
Maine covers 35,387 miles2 (90,300 km2)
North America - 18,000 yBP
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Types of Glaciers
Continental Glaciers
Ice caps, lt50,000 km2
Quelccaya Ice Cap, Peru
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Types of Glaciers
Alpine or Valley Glaciers
Denali, AK
Cirque Glacier, CA
Franz Joseph Glacier, NZ
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Mont Zermatt in Zermatt, Switzerland Dhokela
Yzeiraj
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Formation of Glaciers
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Glacial Advance and Retreat
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Glacial Erosion
Three types of erosion 1. Freeze-Thaw 2.
Plucking 3. Abrasion
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Glacial Erosional Features
Cirque Kluane National Park, YT
U-shaped Valley Yosemite Valley, CA
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Glacier Basin Rocky Mountain National Park
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Franconia Notch, NH Molly Zurheide
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Gros Morne National Park, NF Eoin McCarron
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Harts Location, NH Arran Dindorf
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Glacial Erosional Features Multiple Cirques
Horn Matterhorn, Switzerland
Arête Knife Edge Katahdin, ME
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Glacial Erosional Features
Glacial Polish Acadia National Park, ME
Glacial Striations Newfoundland
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Tenaya Lake, Yosemite NP, CA Ally Bolger
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Glacial Depositional Features
Sediment Types
Glacial Till
Glacial Outwash
Pineo Ridge, near Cherryfield, ME
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Glacial Erratics
Daggetts Rock, Maine left
Doane Rock, Massachusetts right
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Glacial Erratic, Wanaque, NJ Margaret Hunziker
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Glacial Depositional Features Till
Moraines Lateral Medial Terminal
Susitna Glacier, AK
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Mont Zermatt in Zermatt, Switzerland Dhokela
Yzeiraj
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Glacial Depositional Features Outwash
Athabaska Glacier, AB
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Glacial Depositional Features Esker
Esker, MB, above Esker, Sweden, top right Esker,
MI, right
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Glacial Depositional Features Outwash or
Till Kettle Holes and Kettle Lakes
Kettle lakes, MN, above right Kettle lakes, NWT,
right
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Mechanism Driving Continental Glaciation -
Milankovich
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Environmental Implications of Glacial Advance and
Retreat Pollen
Spruce (Abies) pollen
18 ka 14 ka 12 ka 10 ka
8 ka 6 ka
From Jacobson, Webb and Grimm, 1987
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Environmental Implications of Glacial Advance and
Retreat Pollen
Biome transition with glacial retreat
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Evidence of Changes in Glacial Advance and
Retreat
Oxygen Isotopes
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Evidence of Changes in Glacial Advance and
Retreat
Oxygen Isotopes from Ocean Sediments
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Eustatic Sea Level Change
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Ice Cores
Greenland Ice Sheet Project core site
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Ice Cores Interpretation of past atmospheric
composition from gasses
CO2 CH4 N2O
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Ice Cores Dust Influx from Volcanoes and Changes
in Wind and Aridity