Earth's internal heat comes from three main sources:
1) The accretion of dust and gas particles during the Earth's formation released gravitational potential energy and caused internal heating.
2) Radioactive decay of elements in the Earth's core and mantle, such as uranium and potassium, continues to generate heat.
3) Frictional heating from convection currents in the mantle also contributes to the Earth's internal heat. Seismic waves have allowed scientists to indirectly learn about the Earth's layered structure despite only drilling about 7 miles deep.
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L3 EARTH'S INTERNAL HEAT.pptx
1. Earth and Life
Science
Quarter I – Week 3:
Lesson 3:
Earth’s Internal Heat
Supplementary Learning
Materials (SleM)
Writer: LEARNI J. ESCOTE
Content Editor: SANDRA CARETATIVO
Language Editor: PRINCESS A. CAYETANO
Format Editor: VIRNA E. GARCIA
SQAT Chairman: NOEL S. FAVILA, Principal
2. Learning Objectives
Describe where the Earth’s internal heat comes from. (S11/12ES-Ib-14)
Day 1: Describe the effect of the accretion of dust and gas particles on the internal heat
of the earth.
Day 2: Describe the effect of radioactive decays and frictional heating on the internal
heat of the earth Describe how magma is formed (magmatism) (S11/12ES-Ic-15)
Day 3: Explain the three processes that melt the asthenosphere to form magma.
Day 4: Describe the conditions of magma formation
12. • Thinnest layer of the Earth
• Made up of large amounts of silicon and aluminum
• Composed of plates on which the continents and oceans
rest. These “ride” over molten mantle.
• Crust is part of the lithosphere.
• To types of Crust: Oceanic and Continental
Ocean Land
Crust
13. Continental vs. Oceanic Crust
Category Continental Oceanic
Rock Type Granite Basalt
Thickness 5 – 70km (Thicker) 3 – 8 km (Thinner)
State Solid Solid
Crust Age 4 billion years old or
Older
180 million years old
or Younger
Density Less Dense More Dense
Element
Composition
Oxygen, Sodium,
Silicon, Aluminum,
Potassium
Iron, Magnesium,
Calcium
14. TheLithosphere
The crust and the upper layer of the mantle
together make up a zone of rigid, brittle rock called
the Lithosphere.
15. The lithosphere (crust and upper mantle) is
divided into separate plates which move very
slowly in response to the “convecting” part of the
mantle.
16. The Lithospheric Plates
•The crust of the Earth is broken into many pieces called
plates. The plates "float" on the soft, semi-rigid
asthenosphere.
18. The Mantle
The Mantle is the largest layer
of the Earth at 2900 km thick. The
middle mantle is composed of
very hot dense rock that flows like
asphalt under a heavy weight. The
movement of the middle mantle
(asthenosphere) is the reason that
the crustal plates of the Earth
move.
21. Convection Currents
The middle mantle "flows" because of convection currents. Convection
currents are caused by the very hot material at the deepest part of the
mantle rising being less dense, then cooling becoming more dense and
sinking again --repeating this cycle over and over.
22. • Solid but capable of flow (like fudge) Semi-Solid/Semi Liquid
• Thickest layer of the Earth 2900km (1800 miles)
• Element Composition: Magnesium, Silicon, Oxygen, and Iron
• The hot magma rises then cools and sinks.
• These convection currents cause changes in the Earth’s surface.
• Conveyor belt for the tectonic plates.
Upper Mantle
Convection
Currents
Middle
Mantle
Lower Mantle
Mantle
24. Outer
Core
• Composition: Molten (liquid) metal that is about
4,700°C (8,500°F)
• Thickness: 2,266 km (1,400) miles
• State of Matter: Composed of the melted metals
nickel and iron (liquid)
• Located about 1,800 miles beneath the crust.
25. • Solid sphere made mostly of iron and has Nickel
• It is believed to be as hot as 6,650°C (12,000°F)
• Heat in the core generated by the radioactive decay of
uranium and other elements
• It is solid because of the pressure from the outer core,
mantle, and crust compressing it.
• Thickness: 1271 km (800 miles)
Inner
Core
27. What do these two images tell us
about the layers of the Earth?
31. Add this statement to the
arrow going down on your
foldable.
Temperature,
Density and
Pressure increases
as depth increases
32. Which layer of the Earth has the
greatest temperature, pressure, and
density?
Core
33. • How far have scientists
drilled into the
earth?
•7.6 miles
– Only 0.2% of the
distance to the earth’s
core
34. How do we know so much about
what’s under Earth’s surface?
• Through INDIRECT EVIDENCE, mostly
from seismic waves caused by earthquakes
(more on this later this semester...)
• Sometimes indirect evidence is the only option
for scientists to develop a theory
• Lets give it a try...
37. Which of the following statements regarding what we
know about Earth’s interior is most accurate?
A) We have been able to drill into the earth’s core
B) Much about what we know about Earth’s mantle
and core comes from caves and mines
C) We know only about what is on the very surface of
the earth, in what is known as the crust
D) Energy waves allow us to see precisely what is
deep inside the Earth, like a “tricorder” or scanner
from Star Trek
38. Earth’s Interior
What we know about Earth’s interior comes
from indirect avenues of investigation.
Earth’s diameter is approximately 12,756 km
(~ 7,500 miles).
-the deepest hole we have ever drilled
into the Earth is only 9.6 km (~5 mi).
so how do we know what it’s like?
Seismic waves! - natural and man-made
40. Earthquakes
seismic (energy) waves travel through the earth
some energy bounces off harder layers
called reflection
some energy travels through but gets bent, changing the
direction the wave is traveling
called refraction
some energy is absorbed as it encounters materials
called attenuation
Allow us to model what waves show up at given locations,
and when they arrive at given locations.
42. Wave paths are
influenced by
density,
temperature,
and the angles at
which they strike
boundaries as
they travel
through and
around the Earth
43. Factors affect seismic waves
distance: farther = more attenuation
density: higher = faster
temperature: colder = faster
liquid vs solid
- solid = faster; p-waves and s-waves
- liquid = slower; no s-waves
angle of incidence- controls how much is
reflected and how much is absorbed
vertical arrangement of layers
- controls the resultant direction of travel
44. P-wave and S-wave shadow zones
- caused by transmissive and refractive properties of the waves interacting
with rock and liquid
45. Zones of material with distinctive characteristics make up each layer in the Earth
Greatly simplified it
looks like concentric
spheres
46. Crust- the rigid outer shell of the Earth, composed of solid
rock; very thin- averages only 20 km thick (the crust is part of
the Lithosphere)
two kinds of crust
Oceanic- most abundant; consists of rocks formed from mafic
magma; very dense; very thin- 10 km thick
Continental- underlies continents; consists of rock formed
from felsic and intermediate magma; less dense than oceanic
crust; thick-30 to 85 km thick
47. Uppermost mantle- Aesthenosphere
Continental crust
Oceanic crust
Mohorovicic Discontinuity
“The Moho”
Model of Lithosphere and Aesthenosphere showing thickness of Oceanic
vs Continental crust
49. The boundary zone between the crust and the mantle is
called the Mohorovicic Discontinuity or the “Moho”
- a zone of low velocity transmission of seismic waves
Mantle- the semi-solid (jello-like) material underlying the
crust. Extends down to about 3000 km depth
The uppermost part of the mantle is called the
Aesthenosphere.
mostly molten material
50. The mantle is heated closer to the core
Heated mantle material rises upward very slowly
millions of years to move upward
As it near the earth’s surface, the mantle material
liquefies
(due to pressure and temp relationships)
It also begins to cool, and slowly starts to sink back into
the core
This creates a Convection current
53. 3D maps of the earth’s convection currents based on seismic wave analysis-
complicated looking!
54. Earth’s core
Divided into an inner and outer zone
Outer zone is liquid- doesn’t transmit s-waves
Probably composed of Nickel (Ni) and Iron (Fe), some
heavier radioactive elements, along with some other
elements (S or N- Sulfur or Nitrogen)
Inner core is solid- based on speed of P-wave travel
composed of same materials as outer core
Important for generating Earth’s magnetic field
55. Earth’s magnetic field is created by the rotation of the outer
fluid core around the solid inner core
This creates an
electrical current
Generates an
electromagnetic
Field.
Similar to a
bar magnet with
a positive and
negative end
56. Earth’s magnetic field interacts with solar particles, forcing them
to the north or south pole, creating the Aurora Borealis
57. Earth’s magnetic field plays a vital
role in the development of Plate
tectonics theory
Identification of a process that
allows for Sea Floor Spreading.
58. Big Ideas
•The Earth is divided into 3 Main Layers
• Crust
• Mantle
• Core
•Main Rock type of the 2 types of Crust
• Oceanic – Basalt
• Continental – Granite
•Oceanic Crust is denser than Continental
Crust
59. Big Ideas Continued
• The lithosphere is divided into tectonic plates.
• The Mantle has the convection currents which causes
the plates to move.
• The Asthenosphere flows semi-liquid on which the
plates move
• Temperature, pressure, and density increases as depth
increases. This is a direct relationship.
64. Have you ever…
Touched a metal spoon sitting in a pan of
boiling water only to be surprised by HOW hot
it is?
What conducts heat better,
metal or nonmetal? Why?
65. EXAMPLE OF CONDUCTION
• A piece of cheese melts as heat is transferred
from the meat to the cheese (Contact)
66. CONVECTION
• Convection is the movement that transfers heat within fluids
• Fluids = anything that flows
• Heat is transferred by currents within the fluid or gas
67. Examples of Convection:
•Have you ever noticed that the air on
the second floor of your house is
warmer than the first floor? Or that
water in a pool is cooler at the deep
end?
68. Examples of Convection
Convection currents
cause the cooler
breezes you
experience by a large
body of water.
These currents also
cause the movement
of magma within the
earth.
69. RADIATION
• Radiation is the transfer of energy by waves
• What type of waves?
• ELECTROMAGNETIC
• Radiation does NOT require matter to transfer
thermal energy
70. Radiation May Come From
Other Sources
Have you ever sat too close to a campfire?
You’re enjoying the warmth ….. only to notice
that your skin is really warm?
72. As a group come up with two
ideas/inventions where conduction,
convection or radiation can be used to
make society better.
Does not have to be real, but must be
realistic!
Be able to explain how this type of heat
transfer works and makes society better.