ENDOGENIC PROCESS:
MAGMATISM
for Earth & Life Science/Grade 11
Quarter 1 / Module 4
FOREWORD
This self-learning kit will serve as guide to Grade 11 learners in
understanding why the Earth’s internal is hot and where the Earth’s
internal heat comes from. Also, it will help them to explore how
magma is formed and how it is classified.
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OBJECTIVES:
At the end of the lesson, you should be able to:
K: Explain where Earth’s internal heat comes from.
S: Enumerate the different ways on how magma is generated.
Classify magma according to its properties.
A: Recognize the important role of Earth’s internal heat in the
natural cycle.
LEARNING COMPTENCIES:
- Describe where the Earth’s internal heat comes from.
(S11/12ES-Ib-14)
- Describe how magma is formed (magmatism).
(S11/12ES-Ic-15)
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I. WHAT HAPPENED
PRE-ACTIVITIES/PRE-TEST:
Directions: Choose the letter of the correct answer. Write your
answer in your notebook.
1. What drives the Earth’s internal heat engine?
A. oceanic tides
C. solar energy
B. radioactivity
D. volcanoes
2. The temperature of the Earth _____ as the depth _____towards the
core.
A. decreases, decreases
C. increases, decreases
B. decreases, increases
D. increases, increases
3. The process of growth through gradual accumulation of layers is
called _____.
A. acceleration
C. creation
B. accretion
D. formation
4. All are sources of Earth’s internal heat EXCEPT ________.
A. endogenic heating
B. frictional heating
C. heat from formation and accretion
D. radioactivity
5. The core is ________.
A. blue in color
C. very cool
B. made of rock
D. very hot
6. Which of the following magmas has the highest viscosity?
A. Andesitic
C. Intermediate
B. Felsic
D. Mafic
7. Which of the following magmas has the lowest viscosity?
A. Andesitic
C. Intermediate
B. Felsic
D. Mafic
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8. What is magma?
A. Bubbles of gas
B. Carbonic acid in crevices of rocks
C. Molten rock
D. Salt crystals
9. How is magma formed at subduction zone?
A. Frictional heating
B. Increased in pressure leads to melting at the subducting plates
C. Increased in temperature that leads to melting at the
subducting plate
D. Water released from the subducting plate lowers the melting
point of the overlying mantle
10. Magma with low temperature has __________viscosity.
A. equal
C. lower
B. higher
D. no effect
II. WHAT YOU NEED TO KNOW
DISCUSSION:
Recall that there are two geologic processes that occur on
Earth. These are exogenic and endogenic processes.
Exogenic processes are those that originate externally to the
surface of the Earth and is driven by exogenic forces. On the other
hand, endogenic processes are those that occur beneath the
surface of the Earth and is associated with the thermal energy
originating from the interior of the solid Earth.
How hot is the internal of the Earth?
Though not in uniform rate, the temperature of the Earth
increases as the depth increases towards the core. Within the
crust, the geothermal gradient of Earth is about 15° to 30°C per
km. Then, it drops off dramatically through the mantle but
increases more quickly at the base and increases slowly towards
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the core. At the base of the crust, the temperature is
approximately 1000°C, about 3500°C at the base of the mantle
and is estimated to 6000°C at the center of the Earth.
Within the lithosphere, temperature gradient varies depending
on the tectonic setting. It is lowest in the central part of the
continents and higher in parts where plates collide as well as in
boundaries where plates are moving away from each other.
What makes the internal of the Earth hot?
The Earth’s interior heat comes from several sources which
includes heat produced when the planets formed and accreted,
frictional heating and decay of radioactive elements.
Sources of Earth’s Internal Heat
1. Heat from the formation and accretion of planet
This source of heat is a leftover during the formation of planet
around 4.6 billion years ago. It was thought that planetoids had
accreted from dust, hurtled around the sun, and crashed into each
other to formed planets. Moreover, the collisions build up a
surprising amount of heat-over 10,000 Kelvin (9,726.85 °C).
Figure 1Theia planet (Mars-sized object) crashing into the Earth
Source: https://sciencesoup.tumblr.com/post/101207345347/wheredoes -the-earths-internal-heat-come
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The history of Earth’s accretion did not stop there. Three other
major accretion events happened. First, less than 100 million years
after the Earth’s initial formation, Earth, and Theia (a planet, with an
original mass of about 15–45 percent of Earth’s original mass)
merged, increasing Earth’s mass, thus, producing the Moon. This
merging event was considered the most significant after Earth’s
initial formation and had vastly added to Earth’s heat-bank.
Secondly, after the Moon-forming event, Earth received a “late
veneer”-a bombardment by large asteroids and comets. Lastly,
about 3.9 billion years ago, Earth received the late heavy
bombardment of large asteroids and comets.
2. Frictional heating
Frictional heating, caused by denser core material sunk
to the center of the planet. As it sunk, the friction may have
generated heating of as much as 2000 Kelvin or 1726.85°C,
which is smaller than the other sources of heat but still
extremely significant.
3. Heat from the decay of radioactive elements
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Radioactive elements are considered as the major source of
Earth’s internal heat. In the early days about 100 million years, its
radiogenic heat was dominated by short-half-life radioisotopes such
as aluminum-26, cesium-135, hafnium-182, iron-60, neptunium237,
technetium-97, and plutonium-244. When it decays, it releases high
amount of energy.
At present, the radioactive isotopes uranium-235 (235U),
uranium-238 (238U), potassium-40 (40K), and thorium-232 (232Th) in
Earth’s mantle are the primary source. As shown in Figure 2,
radioactive decay produced more heat early in Earth’s history than
it does today, because fewer atoms of those isotopes are left. Heat
contributed by radioactivity is now roughly a quarter of what it was
when Earth formed.
The endogenic processes on Earth are the driving force for
plate-tectonic motion, and for different catastrophic events such
earthquakes and volcanic eruptions that lead to the formation of
different landforms. Also, it is responsible for melting in Earth to
create magmas.
What is magma?
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Figure 3. Difference between magma and lava
Source: https://earthhow.com/lava-magma-difference/
Magma and lava are among of the few words that we often
interchanged but technically, these two words mean different. As
shown in figure 3, the main difference between magma and lava is
its environment. The former is within the interior of the Earth while the
latter is at the surface.
Magma is composed of liquefied. rocks, crystals, and dissolved
gases. It varies in temperature and in chemical compositions. Figure
4. shows the average elemental properties in magma. The most
abundant element is oxygen(O2) which is about 50% of the total,
followed by 25% silicon (Si) and the remaining elements make-up
about the other 25% of the total.
Figure 4. Average elemental proportions in Earth’s crust
Source: https://opentextbc.ca/geology/chapter/3-2-magma-and-magma- formation/
In the previous lesson about layers of the Earth, you learned
that the only part of the Earth that is liquid is the outer core mostly
made up of iron. Based on the data presented in Figure 4, magma
mostly made up of Si and O2, therefore it is not the source of magma
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Where does magma originated?
Magma do not form everywhere beneath the surface of the
Earth. It is formed from the melting of rocks in the Earth’s lithosphere,
which is the lower part of the crust and in the upper portion of the
mantle known as asthenosphere. Rock melts under tremendous
pressure and high temperatures. Molten rock flows like a hot wax.
Most magmas are formed at temperatures between 600°C and
1300°C.
Below is the image of a magma chamber (Figure 4) which
collects magma beneath Earth’s surface. It is located where the
heat
and pressure are great enough to melt rock. These locations
are at
divergent or convergent plate boundaries or at hotpots.
Figure5. Magma Chamber underlying yellow stone
Source: https://flexbooks.ck12.org/cbook/ck-12-middle-school-earth-science-flexbook2.0/section/7.4/primary/lesson/magma-composition-at-volcanoes-ms-es
How are magmas formed?
Temperature and pressure differences as well as structural
formations in the mantle and crust cause magma to form in different
processes.
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Ways to Generate Magma
1. Decompression Melting
Considering the different sources of the Earth’s internal heat
that would cause rock at Earth’s surface to melt, Earth’s mantle is
almost entirely a solid rock. It remains solid at those temperatures
because the rock is under high pressure. Remember that pressure is
the most important factor in the formation of magma. As the depth
increases towards the center of the Earth, the pressure also increases
due to the overlying rocks above. This means that if rock is already hot
enough and pressure is reduced, melting will proceed even without
the addition of heat triggered by a reduction in pressure is called
decompression melting. This process involves the upward movement
of the Earth's mantle to an area where pressure is reduced, and rock
molecules are given more space. Thus, the reduction in overlying
pressure enables the rock to melt, lead in decompression melting to
magma formation.
This process usually occurs at divergent plate boundaries,
wherein the two tectonic plates are moving away from each other. It
also occurs at mantle plumes, columns of hot rocks that rise from the
Earth’s high-pressure core to the lower pressure crust.
2. Increase in Temperature
Though it is considered as the least among the three process,
magma formation is also possible with this process. Recall the previous
lesson on Earths internal heat, as the depth increases towards the
core, the temperature also increases. With the increasing
temperature, the solid rock masses begin to vibrate then the bonding
between them breaks and finally convert into magma.
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3. Flux Melting
This process occurs when impurities such as water H2O or
carbon dioxide CO2 are added to rock. These compounds cause the
rock to melt at lower temperatures. As a result, magma will form in
places
where it originally maintained a solid structure. When addition
of CO2
and H2O takes place in the deep Earth where temperature is
already high, lowering its melting temperature could cause partial
melting of
rock to generate magma.
Furthermore, flux melting also occurs around subduction
zones. In this case, water overlying the subducting seafloor
would lower the melting temperature of the mantle,
generating magma that rises to the surface.
Since magma are less dense than the surrounding rocks,
it will therefore move upward. It tries to escape from the
source through openings such as volcanoes or existing cracks
on the ground. Extrusive or volcanic rock form if magma
crystallizes to the surface while intrusive or plutonic rock form if
it will crystallize before it reaches to the surface.
Types of Magma
Properties of magma depends on the rock that initially
melts, as well as the process that occur during partial melting
and transport.
Table 1. Types of Magma and its Properties
Magma Type
Solidified
Rock
Chemical
Composition
Temperature
Viscosity
Gas Content
Basaltic
or
Mafic
Basalt
45-55 SiO2 %,
High in Fe, Mg,
Ca low in K,
Na
1000 1200°C
Low
Low
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Andesitic
Andesite
or
Intermediate
Felsic
or
Rhyolitic
Rhyolite
55-65 SiO2 %,
Intermediate
in Fe, Mg, Ca,
Na, K
65-75 SiO2
%, low in Fe,
Mg, Ca,
high in K,
Na.
800 1000°C
Intermediate
Intermediate
650 800°C
High
High
Source: geologyin.com/2015/08/magma-characteristics-types-sources-and.html (with slight
modification in viscosity)
Table 1 shows the different types of magma and its properties.
Magma is classified into three, these are Mafic or Basaltic,
Intermediate or Andesitic, and Felsic or Rhyolitic. Take note,
chemical analyses are usually given in terms of oxides of silica (most
commonly, SiO2), since O2 is the most abundant element. In terms of
oxides of silicon, rhyolitic has the highest and basaltic has the lowest
content. On the other hand, basaltic has the highest content of iron
(Fe), magnesium (Mg) and Calcium (Ca) and lowest in potassium
(K) and sodium (Na) while rhyolite has low Fe, Mg, and Ca content
and high in K and Na.
Furthermore, nearly all magmas at the depth of the Earth
contain gases such as CO2, H2O, small amount of S, Cl, and F. As
shown in Table 1, felsic magma has the highest gas contents.
In terms of viscosity, the resistance of a liquid to flow, felsic is the most
viscous while basaltic is the least. It is also shown in Table 1 that
magma with higher SiO2 and with low temperature, most likely to
contain higher number of gases to be more viscous.
In addition, viscosity is a significant property in determining the
eruptive behavior of magmas. As shown in Figure 6, viscous
magmas, like felsic, which are high in silica, tend to stay below the
surface or erupt explosively. On the other hand, if magma is fluid and
runny, like low-silica mafic magma, it is not viscous. This magma often
reaches the surface by flowing out in rivers of lava.
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Figure 6. Volcanic Eruptions
Source: https://flexbooks.ck12.org/cbook/ck -12-middle-school-earth-science-flexbook
2.0/section/7.4/primary/lesson/magma-composition-at-volcanoes-ms-es
III. WHAT I HAVE LEARNED
EVALUATION/POST TEST
Directions:
I. True or False. Write T if the statement is expressing correct
idea and F if the statement is wrong. Write your answer in
your notebook.
______ 1. Frictional heating is considered as the highest source of
Earth’s internal heat.
______ 2. The process of growth through gradual accumulation of
layers is called formation.
______ 3. Oceanic tides drive the Earth’s internal heat.
______ 4. The temperature of the Earth increase as the depth
increases away from the core.
______ 5. Endogenic processes is associated with energy coming
from the interior of the Earth.
______ 6. One of the Laws of Thermodynamics states that heat flow
from hot to cold.
______ 7. In the Earth’s history, formation of moon happened after
the bombardment of asteroid.
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______ 8. Radioactive elements are considered as the least
contributor of heat.
______ 9. The geothermal gradient of Earth is about 15° to 30°C
per km within the mantle.
______10. The estimated temperature of the core is about
6000°C.
______11. Aluminum is the most abundant element present in
magma.
______12. Magma rises toward Earth’s surface because it is less
dense than the surrounding rocks.
______13. Andesitic is more viscous than felsic magma.
______14. Decompression melting involved temperature reduction.
______15. Temperature is considered as the most important factor in
the formation of magma.
II. Filling the blanks. Supply the missing word or words that will
complete the sentence.
1. Process of melting that is triggered by a reduction in pressure is
called _________________________
2. Magma with high viscosity tend to erupt _______________________.
3.Impurities introduced to magma cause the rock to melt
at__________ temperature.
4. ___________is a molten mixture of rock-forming substances, gases,
and water from the mantle.
5. Viscosity is defined as the resistance of fluid to flow and depends
primarily on the composition and___________________ of the
magma.
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REFERENCES
Carlson, Diane H.,Plummer, Charles. C., & Hammersley, Lisa. (2011). Physical
Geology Earth Revealed. 9th ed. McGraw-Hill Companies, Inc., 1221
Avenue of American, New York, NY10020 , 288-289
Characteristics of Magma geologyin.com/2015/08/magma-characteristicstypes-sources-and.html (with slight modification in viscosity
Earth’s
Interior
Heat.
Retrieved
June
25,
2020
from
https://openpress.usask.ca/physicalgeology/chapter/3-3-earthsinteriorheat/
How Magma Formed? Retrieved June 30,2020 from
https://openpress.usask.ca/physicalgeology/chapter/7-1magma-and-how-it- forms/
Introduction to Volcanoes Retrieved July 1, 2020 from
https://www.phivolcs.dost.gov.ph/index.php/volcanohazard/introduction-to- volcanoes
Magma and Magma Formation Retrieved June 29, 2020 from
https://opentextbc.ca/geology/chapter/3-2-magma-and-magmaformation/
Magma Composition at Volcanoes Retrieved July 1, 2020 from
https://flexbooks.ck12.org/cbook/ck-12-middle-school-earthscience-flexbook- 2.0/section/7.4/primary/lesson/magma-compositionatvolcanoes-ms-es
Where does the Earth’s internal heat come from? Retrieved June 25, 2020 from
https://sciencesoup.tumblr.com/post/101207345347/where-doestheearthsinternal-heat-come
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DEPARTMENT OF EDUCATION
SCHOOLS DIVISION OF NEGROS ORIENTAL
SENEN PRISCILLO P. PAULIN, CESO V
Schools Division Superintendent
FAY C. LUAREZ, TM, Ed.D., Ph.D.
OIC - Assistant Schools Division Superintendent
Acting CID Chief
ADOLF P. AGUILAR
OIC - Assistant Schools Division Superintendent
NILITA L. RAGAY, Ed.D.
OIC - Assistant Schools Division Superintendent
ROSELA R. ABIERA
Education Program Supervisor – (LRMS)
ARNOLD R. JUNGCO
Education Program Supervisor – (SCIENCE & MATH)
MARICEL S. RASID
Librarian II (LRMDS)
ELMAR L. CABRERA
PDO II (LRMDS)
AGUSTINA C. OMAGUING
Writer/Illustrator/Lay –out Artists
__________________________
BETA TEAM
ZENAIDA A. ACADEMIA
DORIN FAYE D. CADAYDAY
MERCY G. DAGOY
RANJEL D. ESTIMAR
MARIA SALOME B. GOMEZ
JUSTIN PAUL ARSENIO C. KINAMOT
ALPHA QA TEAM
LIEZEL A. AGOR
EUFRATES G. ANSOK JR.
MA. OFELIA I. BUSCATO
LIELIN A. DE LA ZERNA
THOMAS JOGIE U. TOLEDO
DISCLAIMER
The information, activities and assessments used in this material are designed to provide accessible learning
modality to the teachers and learners of the Division of Negros Oriental. The contents of this module are
carefully researched, chosen, and evaluated to comply with the set learning competencies. The writers and
evaluator were clearly instructed to give credits to information and illustrations used to substantiate this
material. All content is subject to copyright and may not be reproduced in any form without expressed written
consent from the division.
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SYNOPSIS
This Self-Learning Kit describes where the
Earth’s internal heat comes from.
Understanding it is important because it
explains why there are volcanic eruptions
and tectonic activities of the Earth. In addition,
it will be the basis for the different land formation.
Also, this SLK discussed about magma and how
it is generated. Magma is composed of liquefied
rocks, crystals, and dissolved gases. Its properties
depend on the rock that initially melts and the
process that occur during partial melting and
transport. In addition, magma is classified
as mafic, andesitic, and felsic. And is generated
through decompression melting, increase in
temperature and flux melting.
Answer Key
Pre-Test
1. B
6. B
2. D
7. D
3. B
8. C
4. A
9. D
5. D
10. B
Posttest
I.
1. F
6. T
2. F
7. F
3. F
8. F
4. F
9. F
5. F
10. T
II.
1.decompression
melting
2. explosively
3. lower
4. magma
5. temperature
ABOUT THE AUTHOR
Agustina C. Omaguing, is a graduate of
Bachelor of Science in Chemistry at Negros Oriental
State University (NORSU). She earned her Education
units at Foundation University and completed her
academic requirements in Master of Arts in Science
Teaching at NORSU. Currently a Senior High School
teacher at Valencia National High School.
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