Transcript Document 7285266

SHORES AND COASTAL PROCESSES
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.
SHORES AND COASTAL PROCESSES
BEACH NOMENCLATURE
SHORES AND COASTAL PROCESSES
COASTAL DEPOSITIONAL LANDFORMS
SPIT
New Brunswick, Canada
SHORES AND COASTAL PROCESSES
COASTAL DEPOSITIONAL LANDFORMS
HOOK
SHORES AND COASTAL PROCESSES
COASTAL DEPOSITIONAL LANDFORMS
TOMBOLO
Popham Beach State Park, ME
SHORES AND COASTAL PROCESSES
HUMAN INDUCED COASTAL DEPOSITION
BREAKWATERS
SHORES AND COASTAL PROCESSES
HUMAN INDUCED COASTAL DEPOSITION
GROINS
SHORES AND COASTAL PROCESSES
HUMAN INDUCED COASTAL DEPOSITION
JETTY OR JETTIES
Marina del Rey, CA
DESERTS AND WIND ACTION
DESERTS are regions that receive very little rainfall,
generally <25 cm/yr (<10 in/yr) and are sparsely
vegetated.
DESERTS are characterized by dryness, NOT
sandiness.
DESERTS are not devoid of life.
This is the desert.
There’s nothing out here.
Nothing.
-N. Karavasiles
Yuha Desert, CA
DESERTS AND WIND ACTION
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.
DESERTS AND WIND ACTION
TYPES OF DESERTS
SUBTROPICAL DESERTS
Produced by atmospheric convection cells in
equatorial regions.
Sahara Desert, Arabian Desert
DESERTS AND WIND ACTION
TYPES OF DESERTS
RAIN SHADOW DESERTS
Produced on the leeward side of mountain ranges.
Cascades, Sierra Nevada, Rockies
DESERTS AND WIND ACTION
TYPES OF DESERTS
CONTINENTAL INTERIOR DESERTS
Exist because land mass is so large, the interior is
far from ocean moisture sources.
Gobi Desert
DESERTS AND WIND ACTION
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
DESERTS AND WIND ACTION
TYPES OF DESERTS
POLAR DESERTS
Remain cold all year.
Only cold, dry air circulates in these regions.
Greenland, Antarctica
DESERTS AND WIND ACTION
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
DESERTS AND WIND ACTION
WEATHERING IN DESERTS
DESERT VARNISH
DESERTS AND WIND ACTION
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.
DESERTS AND WIND ACTION
WATER IN DESERTS
FLASH FLOOD
Before
After
DESERTS AND WIND ACTION
WATER IN DESERTS
ARROYOS
DESERTS AND WIND ACTION
WATER IN DESERTS
PEDIMENT
PEDIMENTS are gently sloping (<5) erosional
surface produced by erosion at the base of
mountains.
DESERTS AND WIND ACTION
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
DESERTS AND WIND ACTION
STREAM DEPOSITON IN DESERTS
Generally produces ALLUVIAL FANS at the base of
mountains.
DESERTS AND WIND ACTION
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
DESERTS AND WIND ACTION
PLAYA
Death Valley, CA
DESERTS AND WIND ACTION
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
DESERTS AND WIND ACTION
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.
DESERTS AND WIND ACTION
DESERT PAVEMENT
DESERTS AND WIND ACTION
SALTATION
DESERTS AND WIND ACTION
DUNE FORMATION
Navajo Sandstone, UT
DESERTS AND WIND ACTION
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.
DESERTS AND WIND ACTION
LOESS
Dust Bowl, Kansas, 1935
Nef Glacier, Patagonia, Chile
Courtesy of Anna Barensfeld
Glaciers and Ice Caps
Calving glacier in Greenland.
Glaciers and Ice Caps
Types of Glaciers
Continental Glaciers
Greenland - present
Ice sheets, >50,000 km2
Maine covers 35,387 miles2 (90,300 km2)
North America - 18,000 yBP
Glaciers and Ice Caps
Types of Glaciers
Continental Glaciers
Ice caps, <50,000 km2
Quelccaya Ice Cap, Peru
Glaciers and Ice Caps
Types of Glaciers
Alpine or Valley Glaciers
Denali, AK
Cirque Glacier, CA
Franz Joseph Glacier, NZ
Mont Zermatt in Zermatt, Switzerland
Dhokela Yzeiraj
Glaciers and Ice Caps
Formation of Glaciers
Glaciers and Ice Caps
Glacial Advance and Retreat
Glaciers and Ice Caps
Glacial Erosion
Three types of erosion:
1. Freeze-Thaw
2. Plucking
3. Abrasion
Glaciers and Ice Caps
Glacial Erosional Features
Cirque
Kluane National Park, YT
U-shaped Valley
Yosemite Valley, CA
Glacier Basin
Rocky Mountain National Park
Franconia Notch, NH
Molly Zurheide
Gros Morne National Park, NF
Eoin McCarron
Hart’s Location, NH
Arran Dindorf
Glaciers and Ice Caps
Glacial Erosional Features
Multiple Cirques
Horn
Matterhorn, Switzerland
Arête
Knife Edge
Katahdin, ME
Glaciers and Ice Caps
Glacial Erosional Features
Glacial Polish
Acadia National Park, ME
Glacial Striations
Newfoundland
Tenaya Lake, Yosemite NP, CA
Ally Bolger
Glaciers and Ice Caps
Glacial Depositional Features
Sediment Types
Glacial Till
Glacial Outwash
Pineo Ridge, near Cherryfield, ME
Glaciers and Ice Caps
Glacial Erratics
Daggett’s Rock, Maine
left
Doane Rock, Massachusetts
right
Glacial Erratic, Wanaque, NJ
Margaret Hunziker
Glaciers and Ice Caps
Glacial Depositional Features
Till
Moraines
Lateral
Medial
Terminal
Susitna Glacier, AK
Mont Zermatt in Zermatt, Switzerland
Dhokela Yzeiraj
Glaciers and Ice Caps
Glacial Depositional Features
Outwash
Athabaska
Glacier, AB
Glaciers and Ice Caps
Glacial Depositional Features
Esker
Esker, MB, above
Esker, Sweden, top right
Esker, MI, right
Glaciers and Ice Caps
Glacial Depositional Features
Outwash or Till
Kettle Holes and Kettle Lakes
Kettle lakes, MN, above right
Kettle lakes, NWT, right
Glaciers and Ice Caps
Glaciers and Ice Caps
Mechanism Driving Continental Glaciation - Milankovich
Glaciers and Ice Caps
Environmental Implications of Glacial Advance and Retreat
Pollen
Spruce (Abies) pollen
18 ka
14 ka
12 ka
10 ka
From Jacobson, Webb and Grimm, 1987
8 ka
6 ka
Glaciers and Ice Caps
Environmental Implications of Glacial Advance and Retreat
Pollen
Biome transition
with glacial retreat
Glaciers and Ice Caps
Evidence of Changes in Glacial Advance and Retreat
Oxygen Isotopes
Glaciers and Ice Caps
Evidence of Changes in Glacial Advance and Retreat
Oxygen Isotopes from Ocean Sediments
Glaciers and Ice Caps
Eustatic Sea Level Change
Glaciers and Ice Caps
Ice Cores
Greenland Ice Sheet Project core site
Glaciers and Ice Caps
Ice Cores
Interpretation of past atmospheric composition from gasses
CO2
CH4
N2O
Glaciers and Ice Caps
Ice Cores
Dust Influx from Volcanoes and Changes in Wind and Aridity