FORCES ON EARTH - Flipped Out Science with Mrs. …...Geologists –scientists who study the forces...
Transcript of FORCES ON EARTH - Flipped Out Science with Mrs. …...Geologists –scientists who study the forces...
An investigation into how Newton’s Laws of Motion are applied to the tectonic activity on Earth.
FORCES ON
EARTH
Geologists – scientists who study the forces that make and shape the Earth
GEOLOGY
• Destructive – slowly wear
away mountains and every
other feature on Earth
•Constructive – shape the earth by building up mountains and landmasses
Geologists divide the forces that change the Earth into two categories:
SO….HOW DO WE KNOW WHAT’S INSIDE THE EARTH?
• Geologists record seismic waves and study how they travel through the medium of Earth.
• The speed and the path the waves takes reveal how the planet is put together.
• The further “in” you go… temperatureand pressure both increase
• There are three main layers that make up the Earth’s interior:
• Crust
• Mantle
• Core
A JOURNEY TO THE CENTER OF THE EARTH
• The layer of rock that forms Earth’s outer skin
• It consists of about 10 miles of rock
• Continental crust is thicker than oceanic crust
• However, oceanic crust is much denserthan continental crust
THE CRUST
• The mantle extends to a depth of approximately 1,800 miles
• It is made of a thick solid rocky substance
• The uppermost part of the mantle and the crust together form a rigid layer called the lithosphere
• The asthenosphere is super-heated rock(molten)
• The remainder of the mantle is solid
THE MANTLEUpper mantel
Lower mantel
Lithosphere (hard)
Asthenosphere (soft)
Mesosphere
• Consists of two parts
• Outer core – molten iron and nickel metal
• Inner core – solid dense ball of iron and nickel metal
THE CORE
• Heat is transferred through:• Radiation• Conduction• Convection
• Let’s go through what each type of heat is first, before we apply it to the Earth.
CONVECTION CURRENTS AND THE MANTLE
• Radiation – transfer of energy by electromagnetic waves (ex. Sun heating the Earth)
RADIATION
• Conduction –the process by which heat energy is transmitted through collisions between neighboring molecules. Think of a frying pan set over an open camp stove. The fire's heat causes molecules in the pan to vibrate faster, making it hotter.
CONDUCTION
Heat Transfer
• Convection - The transfer of heat energy by movements of a fluid.
• heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it.
• The heating and cooling of a fluid, changes in the fluid’s density, and the force of gravity combine to set convection currents in motion.
• Convection currents continue as long as heat exists!
CONVECTION
• Heat from the Earth’s core and from the mantle itself cause the convection currents in the mantle
• Convection currents are an unbalanced force that causes heat flow and the movement of material within the earth.
• This moving material results in earthquakes and volcanic eruptions to create mountains and ocean basins.
CONVECTION IN THE MANTLE
• The crust is broken into large pieces, which we call “plates”
TECTONIC PLATES – WHAT ARE THEY?
• Plate movement result in stress within the Earth’s crust which adds energy to rock until the rock either breaks or changes shape
PLATE MOVEMENT
• Plates apply equal and opposite forces on each other. (A push or pull )
• The acceleration of the plate depends on forces acting on the plate and the mass of the plate.
PLATES AND FORCES
http://education.sdsc.edu/optiputer/flash/co
nvection.htm
EFFECTS OF PLATE TECTONICS
*There are several geological processes that occur where plates meet (at the plate edges):
1. Volcanoes tend to erupt at plate margins as a result of a process called subduction
2. Earthquakes occur where plates grind against or over one other
3. Mountain building occurs as one plate is pushed over another
4. Seafloor spreading occurs where two oceanic plates pull apart, makes ocean basins
THE 3 TYPES OF PLATE BOUNDARIES
CONVERGENT BOUNDARIES• Convergent Boundaries are the boundaries between
two plates that are converging, or moving towards each other.
• Earthquakes, island formation, mountain forming, and volcanoes all occur as the result of these plate collisions.
• When two plates collide (converge) one plate moves under the other.This process is called “subduction.”
• There are three types of convergent boundaries
“Convergent, means to come together.”
TYPES OF CONVERGENT BOUNDARIES
Oceanic/oceanic Subduction occurs
Oceanic/continental Oceanic plate sinks
Continental/continental Mountain ranges form
Let’s look at a few examples:
WHAT CAN HAPPEN AT EACH BOUNDARY?
Convergent
boundary of two
oceanic plates.
Creates an island arc and
a trench.
A trench is like a deep
canyon, but in the ocean.
Example: Japan
Mariana Trench
The most famous trench in the world:
Oceanic plate and
a continental plate.
Forms a volcanic
mountain range and
a trench.
Example: Andes Mts
Continental-Continental
Convergent Boundary
The convergent
boundary of the Eurasian
and Indian Plates has
resulted in the formation
of the highest mountain
range in the world – The
Himalayas
This illustration shows
the movement of the
land mass known as
India today. As it moved
on the Indian plate through
time, over millions of years,
it finally collided with the
Eurasian plate forming the
Himalayan Mountains
Mount Everest is the tallest mountain in the
world, at over 29,000 ft. and is part of the
Himalayas. This is a result of the Eurasian
and Indian Plates colliding and it is still
getting higher as these two plates continue
to collide.
DIVERGENT BOUNDARIES
• Divergent Boundaries are the boundaries between two plates that are diverging, or moving away from each other.
“Divergent, means to spread apart.”
When plates are spreading apart from one another there is a lot
of geological activity. Earthquakes and volcanoes occur here.
•In some places like in East Africa, a rift valley can form that is
hundreds of feet deep.
Aerial view of Africa’s Rift Valley
The Mid-Atlantic Ridge is one of the
world’s largest divergent plates,
running North to South in just about
the center of the Atlantic Ocean.
All along this ridge, volcanic activity
takes place and the sea floor is
spreading East and West at a rate of
1.25 cm per year.
Question: So what is happening on the
other side of that same plate?
Divergent Boundary Between the
Eurasian and North American Plate
TRANSFORM FAULT BOUNDARIES
• Transform Boundaries are the boundaries between two plates that are sliding horizontally past one another.
“Transform, means to slide past one another.”
PLATES MOVE SIDE BY SIDE
• Transform boundaries neither create nor consume crust. Rather, two plates move against each other, building up tension, then releasing the tension in a sudden and often violent jerk. This sudden jerk creates an earthquake.
Earthquakes in Austin
There is a transform-fault boundary where the North American and Pacific
plates are moving past each other.
Example: San Andreas fault in California
Strike Slip Faults
The San Andreas Fault, seen
here, is the result of the Pacific
Plate sliding past the North
American Plate. This is the site
of many of the earthquakes that
occur in the United States
• Plate movement can alter Earth systems and produce changes in Earth’s surface
• Deformation of the crust
• Faults
• Mountain building
• Land subsidence
• Volcanoes
CHANGING EARTH’S SURFACE
• A volcano is a weak spot in the crust where molten, rock-forming magma comes to the surface
• Volcanic activity builds mountains made of lava rock and other volcanic materials
VOLCANOES
• There are more than 600 active volcanoes on land and many more beneath the sea
• Volcanic belts form along the boundaries of Earth’s plates.
• One major volcanic belt is the Ring of Fire
LOCATION OF VOLCANOES
Ring of Fire – very active region of subduction
RING OF FIRE
http://www.volcano.si.edu/players.cfm?pid=2
RECENT EARTHQUAKES AND VOLCANIC ERUPTIONS
• All seismic activity occurs along plate boundaries (except for hotspots)
• Magma rises through the mantle forming an active volcano
• The plate moves over
this spot forming a
chain of islands with
the active volcano
being the one over
the hot spot
WHAT ARE HOT SPOTS?
Hot Spot Volcanoes
HOW IT WORKS
EARTH’S INTERIOR G.O.
• Get a computer and begin working on the web-quest.
• Follow the questions and it will lead you through the online activities.
• This is due –
Wed. March 23 (but you could get it done in class - today!!)
WEB-QUEST!