Transcript The Changing Earth

The Changing Earth
Video Clip: Intro - 1:34
http://www.edu.pe.ca/southernkings/Pictures/fault5.gif
Pangaea B6-9
http://www.exploratorium.edu/faultline/earthquakescience/images/pangea_lrg.gif
• Pangaea in motion
Pangaea B6-9
• one giant land mass of all of the continents
• 200+ million years ago
2:23
The Theory of Continental Drift B10-12
• Alfred Wegener suggested idea that
land started as Pangaea, but continents
have drifted to their present positions.
3:15
Evidence for Continental Drift B10-15
1. puzzle-piece fit (especially SA/Africa)
2. fossil remains on separate continents
3. same rock layer patterns on separate continents
4. fossils of temperate plants in current polar
regions
5. evidence of glaciers in currently warm climates
Earth’s Layers B19
Earth's layers
• 1. Crust: the thin, outer
layer of Earth
• 2. Mantle: hot solid (9002,000°C) 2,900 km thick
• 3. Outer Core: liquid metal
(may be iron and nickel)
• 4. Inner Core: solid metal
(5,000°C in some places)
1:16
http://www.geog.ouc.bc.ca/physgeog/contents/i
mages/earthcut.jpg
3 Types of Rocks in the Crust
website
• Igneous – cooled, hardened lava
• Sedimentary – layered rock
• Metamorphic – igneous and sedimentary
rocks that have been CHANGED by heat
and pressure
Theory of Plate Tectonics B19-21 & B38-40
• Theory that Earth’s crust
is broken into enormous
plates that are in motion
• Continents still drifting
about 10cm/year
• Most volcanoes and
earthquakes occur at
PLATE BOUNDARIES
1:21
Lithosphere & Asthenosphere
1:17
B38-39
• Lithosphere – crust and upper mantle;
solid rock (8-64 km thick)
• Asthenosphere – the area of the mantle
where the rock is soft and slightly melted
• Convection current – churning heating
and cooling of magma inside the Earth
causing tectonic plates to move (like
boiling rice)
Theory of Plate Tectonics B19-21
Fault = large crack in Earth’s surface due to
movement of plates
1:25
Tectonic Plate Movement & Plate
Boundaries B40-41
Plate Boundaries
Plate Movement
Example
Convergent ><
Colliding ><
Mountains/
Volcanoes
Divergent < >
Separating < >
Sea-Floor
Spreading
Transform-fault
Sliding
Causes
Earthquakes
Tectonic Plate Movement B40-41
http://www.mrd.gov.fj/gfiji/geology/educate/platect.html
Mountains B45-50
Folded – when masses of rock are squeezed from
opposite sides (two plates collide).
2. Fault-Block – when blocks of rock move up or
down along a fault.
3. Dome – when the surface is lifted up by magma.
4. Volcanic -magma erupts from opening in Earth’s
surface
Video Clip: Mountains - 2:46
1
Mountain Maps
http://www.anamericandream.net/testimonials.htm
Tallest Mountains
Tallest Mountain in the World:
Mt. Everest Asia 8,708m
http://1.im.cz/n/photo/00/54/08blisj-topsirka.jpg
B49
Tallest North American Mountain:
Mt. McKinley AK 6,096 m
http://www.fostertravel.com/akflyi102web.jpg
Earthquakes B58-61
•vibration of earth caused by release of
energy as plates shift past one another
•can last for a few minutes
•Aftershock - shock that occurs after the
initial shock of an earthquake – can be felt
many miles away
•Earthquake occurrences
USGS website
Measuring Earthquakes B59-61; B74-75
Richter Scale
• used to measure
magnitude (amount of
energy) of earthquake
• Scale of 0-9
Measuring Earthquakes B59-61; B74-75
Seismograph
• used to record the intensity,
duration, and nature of
earthquake waves
http://www.isgs.uiuc.edu/earthquakes/Images/ss-80_display_seismograph.jpg
Epicenter and Focus B56
• Epicenter – the place
on Earth’s surface
directly above the
origin of the quake
• Focus – The exact
location of where the
earthquake started
(underground)
http://www.bedford.k12.ny.us/flhs/science/images/epicenter.jpg
Earthquake Faults B64-65
• Fault – crack in Earth’s crust where
movement occurs
• Types of faults (only the first 3)
– Normal
– Reverse
– Strike/Slip
San Andreas fault ~ California
Final Thoughts on Earthquakes
Video Clip: Earthquake – 20:00
Tsunami B76-77
• Created by earthquake under water
• Most common along Pacific coastal
areas
• Large wave of water that builds power
as it moves into shallower water
• Causes massive destruction
• Most recent was Indonesia/Sri Lanka
area
– 2004 Richter Scale = 9.0 > 280,000 died
Video Clip:
Tsunami – 43:00
Volcanoes B86-89
• any opening in Earth’s crust through which
hot gases, rocks, and melted material erupt.
• Magma = melted material contained
beneath Earth’s surface
• Lava = magma that has reached the earth’s
surface [can be higher than 1,100°C
(2,000°F)]
Video Clip: Volcanoes – 1:00
4 Steps in a Volcanic Eruption B86
website
STEPS:
1. High temperatures &
pressures deep within Earth
cause rock to melt.
2. Magma makes its way toward
the Earth’s surface melting
surrounding material to form
a central pipe.
3. Hot melted material moves
through the volcanic vent.
Ring of Fire B87
Ring of Fire -area along the coastlines of
NA/SA and Asia/Australia where there are
more than 500 volcanoes
Video Clip: Ring of Fire – 0:45
Types of Volcanic Activity B88
• active – erupts constantly
• intermittent – erupt on a regular basis
Mt. St.
Helens
site
• dormant – volcano that has not erupted in a
long time
• extinct – no record of volcano ever erupting
3 Types of Volcanoes
Video Clip: Types of Volcanoes – 4:00
Cinder-Cone Volcanoes B88
• explosive eruptions where layers of cinders
land near central vent
• small with steep slopes
• bowl-shaped craters on top
• formed in groups
• ex. Paricutin in Mexico
Cinder-Cone Volcano
Shield Volcanoes B89
• lava flows quietly from crack
• larger with gentle slopes
• ex. Mauna Loa (Hawaii) largest volcano
Shield Volcano
Composite-Cone Volcanoes B89
• explosive eruptions alternate w/ quieter
oozes (mix of the two)
• steeper near top, but gentle slopes close to
the base
• most destructive – often occur w/o warning
• ex. Mt. Vesuvius
Composite–Cone Volcano
Hot Spots B102-103
•
•
•
•
extremely hot places deep within the Earth’s mantle
blowtorch from below
hot spot does not move, but plates move over it
Video Clip: Hot Spots - 0
Ex. Hawaii
Video Clip: Hawaii - 0
Caldera B102-103
• large circular depression formed when part
of a volcano collapses
The Changing Earth - Review
You will need to know:
1. Wegener’s theory of continental drift & be able to give reasons to
support it
2. theory of plate tectonics & why the plates move as they do
3. how to identify the layers of the Earth
4. the three types of rocks found in the Earth’s crust
5. the types of plates, their characteristics, & the type of boundaries they
have
6. the types of mountains and their descriptions
7. the difference between the focus and the epicenter of an earthquake
The Changing Earth - Review
8. the difference between a seismograph and the Richter scale
9. what tsunamis and calderas are
10. the difference between magma and lava
11. where the Ring of Fire is located and how many volcanoes are
located there
12. the types of volcanoes and their descriptions
13. the descriptions of the terms for volcanic activity
14. how the islands of Hawaii were formed