SLOW Processes
that Shape the Earth
PART 2. EROSION
Mrs. Wright
Hugh B. Bain Middle School
Cranston, RI
Earth - developed over long periods of time
through continual change processes.
STUDENTS:
 Evaluate slow processes of
1) weathering 2) erosion and 3) mountain building.
The following slides are on erosion.
 Determine how the earth has changed and will continue
to change over time.
EROSION
Process by which natural
forces or agents (wind,
water, ice, or gravity) move
weathered rock and soil
from one place to another
cover0116-sediment.jpg
creek edge showing
tiers of sediment deposition & gravel
northcoastjournal.com
Sediment
Deposition
 Material moved by erosion
 Occurs where agents of
(pieces of rock, soil, plant,
& animal)
erosion deposit sediment
& changes shape of land
Causes of Erosion
1. Gravity
2. Running Water
3. Glaciers
4. Waves
5. Wind
1. Gravity
What is gravity ?
Force that moves rock and other materials
downhill causing mass movement
Types of Mass Movement
Caused by Gravity
A. Landslides
B. Mudflows
C. Slump
D. Creep
A .a FAST Process Landslides
 Occurs when
landslide.jpg
In my earlier post, we discussed the causes of landslides.
kshitija.wordpress.com
rock & soil slide
quickly down a
steep slope
 Most destructive
B. a FAST Process Mudflows
• Rapid
downhill
movement
of a mixture
of water,
rock, & soil
ueol_02_img0070.jpg scienceclarified.com
C. a FAST Process Slump
 Mass of rock &
slump1.jpg Slump at Double Ditch - April, 1988 (Burleigh County, N.D.) more mass ... umt.edu
soil suddenly
slips down a
slope in one
large mass (often
when water
soaks bottom of
clay soil)
D. Creep
 Very slow downhill
movement of rock
& soil (often from
freezing & thawing
of water in cracked
layers of rock
beneath soil
creep_kathryn1.jpg shoop2010.weebly.com
2. Running Water
Major agent of erosion that
shaped Earth’s land surface
Raindrops loosen soil
& carry particles.
splash_eriosion.jpg Raindrop
Runoff
•Water that
runs over the
Earth’s surface
runoff.jpg
Surface runoff
absoluteastronomy.com
Forms of Runoff
(smallest to largest):
Rills →Gullies →Streams → Rivers → Lake
Running Water - Runoff
 Rill →
rill.jpg
 Gully →
A channel
with water
only after it
rains
runoff-670291.jpg
 Stream →
9907_05_15---Stream_web.jpg Stream freefoto.com
 River →
falls-river-towards-sheep-falls.jpg rivers flyfishingfrenzy.com
 Lake →
Vg-025.jpg large lake shannontech.com
Rivers
• Through
falls-river-towards-sheep-falls.jpg
rivers flyfishingfrenzy.com
erosion,
rivers can
create a
variety of
features
River Features
A. Valleys
B. Waterfalls
C. Floodplains
D. Meanders
E. Oxbow lakes
A. Valley
• Elongated
low area
between hills
formed by a
stream
258530373_87b9bf351d.jpg
Kullu Valley's Beas River
formed ...
flickr.com
B. Waterfall
• Occur where a
river meets rock
that erodes
slowly & flows
over softer rock
downstream
waterfallLG.jpg
Largest waterfall in Lesotho, Africa
todayscampus.com
C. Floodplain
• Flat, wide area of land
along river.
• Lower down on its
course where land
slopes gently, river
spreads out forming a
river valley
• Floodplains here
floodplain.jpg floodplain belmont.sd62.bc.ca
D. Meander
• Loop-like
bend in the
river (S
shape Mississippi)
meander_word_picture.jpg Meandering csahf.blogspot.com
E. Oxbow Lake
• Meander
that has
been cut
off from
the river
• Horseshoe
shape
Oxbow_lake,Yamal_Peninsula,Russia.JPG
dic.academic.ru
agilogy.com
Oxbow Lake
• During a flood,
high water finds a
straighter pass
downstream
• As water falls,
sediments dam up
ends of meander
Forming an Oxbow 111232009.jpg
Oxbow Lakes Kentucky, United States ...
geocaching.com
3. Glaciers
What are glaciers?
Any large mass of ice that moves slowly over land
Types of Glaciers
A. Continental Glaciers
B. Valley Glaciers
• Covers much of a continent
A. Continental Glacier
• Flow in all directions as
they move (like pancake
batter in frying pan)
• In distant past – covered
one third of Earth’s land
• Have advanced, then
retreated (last time 10,000 yrs ago), or
melted back, several
times
ContinentalIce.jpgThe Continental Ice Sheet is the
most significant of all the glacial agents ...
homepage.montana.edu
• Long & narrow glacier
• Forms when snow & ice
build up high in a
mountain valley
B. Valley Glacier
• Sides of mountain
keep them from
spreading out in all
directions
• Usually move down
valleys already cut by
rivers
• Much smaller than
continental glaciers
Tidewater-Glacier.jpgThere are an estimated
100000 valley glaciers travelwithachallenge.com
Processes of Glacial Erosion
A. Plucking
B. Abrasion
A. Plucking
• Glacier picks up
rocks as it flows over
land;
• Rock fragments &
boulders freeze to
glacier bottom &
are carried.
030515_75mhadaidh.jpg
PLUCKING – a type of erosion. geogars.wordpress.com
B. Abrasion
• Many rocks
remain on
bottom &
get dragged
along
• Gouges &
scratches
bedrock
striations.jpg Abrasion sometimes results in
striations (scratches on the bedrock)…
geogars.wordpress.com
Landforms from Glacial Deposition
A. Till
B. Moraine
C. Kettle
A. Till
• Mixture of sediments
(sand, silt, clay,
boulders) deposited
directly on surface
till2.gif
Area adjacent to Sherman glacier is covered with a coarse glacial till.
pubs.usgs.gov
• Till deposited at edges of glacier
form ridge (Long Island, NY)
B. Moraine
03 river-thumb-608x456.jpg
Much of New York's Long
Island was once the ...
blogs.nationalgeographic.com
C. Kettle
• Depression formed
when ice is left in
glacial till
• When ice melts,
kettle remains
forming ponds or
kettle lakes
kettle1.gif The largest kettle shown is ~ 150 feet in diameter.
Bering Glacier flows ... pubs.usgs.gov
4. Waves
Form from wind that blows across water’s surface
Shape coast through erosion by breaking down rock
& transporting sand & other sediment.
Landforms Created by Wave Erosion
A. Headland
B. Sea Arch
C. Sea Cave
D. Sea Stack
E. Wave Cut Cliff
A. Headland
• Part of shore
sticks out into
ocean
• Made of hard
rock that
resists erosion
longer
headland_soldiers_rock.jpg
Headland right of Soldier's Rock
islaygallery.com
sea-arch-volcan
oes-national.jpg
Sea arch Volcanoes
National Park
tripadvisor.com
070906-045.jpg
Ilena in her kayak going
through a sea arch(cave) on
...bryanhansel.com
the_other_way.1212007
260.sea-arch.jpg
Sea arch, Tutukaka,
New Zealand. Poor
Knights Islands
travelpod.com
B. Sea Arch
Folga Skerry.jpg
Sea Caves
landforms.eu →
Sand Island Sea Caves.
jpg
Madeline Island Sea
Caves. Top Canoe
destination in the
world, ...
en.petitchef.com ↓
C. Sea Cave
Sea+Cave.jpg
Just one of many sea caves
seen on the trip.
↓kauai-artist.blogspot.com
D. Sea Stack
IMG_3180.jpg Sea Stacks
ideaphore.org
Climbers_on_the_450ft_Sea_Stack_Old
_Man_Of_Hoy,_Orkney.jpg
Climbers on the 450ft sea stack Old
Man Of Hoy, Orkney heason.net
E. Wave Cut Cliff
calif_wavecutcliff.jpg wave cut cliff www2.pvc.maricopa.edu
Deposits by Waves
A. Beach
B. Longshore Drift
C. Sandbar
D. Barrier Beach
A. Beach
EastBeach2.JPG
East Beach ...
riparks.com
• Waves repeatedly hit beach,
beach sediment moves down
beach with current
B. Long Shore Drift
• spit – beach that projects
out like a finger result of
longshore process
CapeFear.jpg longshore drift.
geolab.unc.edu
dungeness-spit.jpg
Dungeness Spit,
Straight of Juan de Fuca
livingwilderness.com
• Long ridges of sand parallel to shore
Australia_Lakeland_Island_Sand_Bar.jpg
735 × 450 - Lakeland Island Sand Bar
australiaadventures.com
C. Sand Bar
D. Barrier Beach
• Form when storm
waves pile up large
amounts of sand
forming long,
narrow island
parallel to coast
14.jpg
Gravel barrier beach, Coombs Cove, Hermitage Peninsula.
gsc.nrcan.gc.ca
Wave Terms
A. Impact
B. Abrasion
A. Impact
• Large waves
hit rocks with
force & break
apart rocks
stock-photo-small-wave-impact-stone-55974676.jpg
small wave impact stone
shutterstock.com
B. Abrasion
• Wave in
shallow
water picks
up sediment
that hits land
where it
wears away
at rock
coast.jpg
AbrasionWave Pounding
sixthsense.osfc.ac.uk
5. Wind
Wind causes erosion by:
A. Deflation
B. Abrasion
A. Deflation
• Process where
wind removes
surface
materials
deflation_sm.jpg
deflation
belmont.sd62.bc.ca
B. Abrasion
• May polish
rocks but
causes little
erosion
rock_wind_abrasion_p077
2932441_NRCS.jpg
Figure 20.4 Rock sculpted
by wind, Utah.
Courtesy NRCS
uwsp.edu
Deposition Forms:
A. Sand Dunes
B. Loess Deposits
A. Sand Dunes
egypt-sand-dunes-30063
2-ga.jpg
Photo: Sand dunes ...
photography.nationalgeo
graphic.com
B. Loess Deposits
• Very fine
sediment made
up of silt &
clay so it
travels far
D015-060.jpg
Loess Deposits
facweb.bhc.edu
Looking at the SLOW process of
erosion just discussed, how has the
earth changed over time?
Is it still changing? How do you know?
Give at least three examples.