Volcanicity, Processes, Regions and Volcanic Landforms for SS 3

Class: Senior Secondary School 3 (SS3 / SSS 3)
Term: 1st Term
Week: 2
Age: 17 years
Duration: 45 minutes
Subject: Geography
Curriculum Theme: Geography
Previous Lesson: Earthquakes, Meaning, Causes, Regions and Effects
Topic: Volcanicity
Subject Matter: Meaning of volcanicity, volcanic processes such as crustal disturbances, intrusion and extrusion, eruption and emission, regions of volcanic occurrence, intrusive features or landforms, extrusive features or landforms, effects of volcanicity

Specific Objectives

By the end of the lesson, students should be able to:

Cognitive Domain:

• Define volcanicity.
• Describe various volcanic processes.
• Identify major regions where volcanic activity occurs.
• Explain the formation of intrusive and extrusive volcanic landforms.
• State the positive and negative effects of volcanicity.

Affective Domain:

• Appreciate the powerful natural forces that shape the Earth’s surface.
• Show interest in learning about geological phenomena.

Psychomotor Domain:

• Draw simple diagrams illustrating volcanic features.
• Locate and mark major volcanic regions on a world map.

Social Domain:

• Participate actively in class discussions about volcanicity.
• Collaborate with peers during map work activities.

Reference Materials

The following resources were used in planning this lesson:

• FCT-ERC SS 3 Scheme of Work, September 2014 curriculum.
• Relevant State Unified Scheme of Work.
• A suitable Geography textbook for SS 3.

Instructional Materials

The teacher will teach this lesson with the aid of:

• Documentary films on volcanic eruptions
• Video clips illustrating volcanic processes and features
• A large world map showing tectonic plates and volcanic zones
• Diagrams and sketches of intrusive and extrusive landforms
• Drawing paper and tracing paper for students

Rationale for the Lesson

Understanding volcanicity helps students to comprehend how the Earth’s internal forces create and modify landforms. It also enables them to recognize the natural hazards and benefits associated with volcanic activity, which is important for understanding their environment.

Prerequisite/Previous Knowledge

Students have basic knowledge of the Earth’s structure, tectonic plates, and internal forces from previous geography lessons.

Lesson Content/Board Summary

Volcanicity

Meaning of Volcanicity

Volcanicity refers to all phenomena connected with the movement of molten rock (magma) from the Earth’s interior to the surface. It includes the eruption of gases, ash, and lava, and the formation of various landforms.

Volcanic Processes

Volcanic activity involves several processes:

1. Crustal Disturbances: Movements within the Earth’s crust, often related to plate tectonics, create cracks and weaknesses through which magma can rise.
2. Intrusion and Extrusion:
   1. Intrusion: Occurs when magma forces its way into existing cracks and weaknesses within the Earth’s crust but does not reach the surface. It cools and solidifies underground.
   2. Extrusion: Occurs when magma (now called lava) reaches the Earth’s surface through vents or fissures and flows out.
3. Eruption and Emission:
   1. Eruption: The violent expulsion of molten rock, ash, and gases from a volcano.
   2. Emission: The release of gases and steam from volcanic vents, often without a full eruption.

Regions of Volcanic Occurrence

Volcanoes are not evenly distributed across the Earth’s surface. They are mostly found in specific zones, which include:

1. The Pacific Ring of Fire: This is the most active volcanic zone, encircling the Pacific Ocean. It accounts for about 75% of the world’s active and dormant volcanoes. Examples include Mount Fuji (Japan), Mount St. Helens (USA).
2. The Mid-Atlantic Ridge: A divergent plate boundary where new crust is formed, leading to volcanic activity, often underwater. Iceland is a prominent example of sub-aerial volcanism along this ridge.
3. The Mediterranean Belt: This zone extends from the Atlantic Ocean, through the Mediterranean Sea, to Asia. Examples include Mount Vesuvius (Italy), Mount Etna (Italy).
4. East African Rift Valley: A zone of continental rifting with numerous volcanoes, such as Mount Kilimanjaro (Tanzania) and Mount Kenya (Kenya).

Intrusive Features or Landforms

These landforms are created when magma solidifies beneath the Earth’s surface. They are exposed later by erosion of the overlying rock:

1. Batholith: A large, irregular mass of intrusive igneous rock, often forming the core of mountain ranges.
2. Laccolith: A mushroom-shaped intrusion that pushes overlying sedimentary rock layers upwards.
3. Phacolith: A lens-shaped intrusion found in the crests or troughs of folded rock strata.
4. Lopolith: A large, basin-shaped intrusion with a depressed central portion.
5. Sill: A tabular intrusion that runs parallel to the bedding planes of existing sedimentary rocks.
6. Dyke (or Dike): A tabular intrusion that cuts across the bedding planes of existing rock layers.
7. Volcanic Neck/Plug: The solidified magma column within the vent of an extinct volcano, exposed after the erosion of the cone.

Extrusive Features or Landforms

These are landforms created when lava, ash, and gases erupt onto the Earth’s surface.

1. Volcanic Cones: Hill-shaped landforms built up by layers of lava and ash. Types include:
   1. Shield Cones: Broad, gently sloping cones formed by highly fluid basaltic lava (e.g., Mauna Loa, Hawaii).
   2. Cinder Cones: Steep-sided, symmetrical cones built from ejected fragments of lava (cinders) (e.g., Parícutin, Mexico).
   3. Composite Cones (Stratovolcanoes): Steep-sided, symmetrical cones built from alternating layers of lava flows, ash, and rock fragments (e.g., Mount Fuji, Japan).
2. Craters: Bowl-shaped depressions at the summit of a volcano, formed by explosive eruptions.
3. Calderas: Large, basin-shaped depressions, much larger than craters, formed when the summit of a volcano collapses after a massive eruption.
4. Lava Plateaus (Basalt Plateaus): Extensive, flat-topped regions formed by successive outflows of highly fluid basaltic lava through fissures (e.g., Deccan Traps, India).
5. Geysers: Hot springs that intermittently eject a column of hot water and steam into the air (e.g., Old Faithful, Yellowstone National Park).
6. Hot Springs/Thermal Springs: Springs that produce geothermally heated groundwater.

Effects of Volcanicity

Volcanic activity has both positive and negative effects on the environment and human life.

Positive Effects:

1. Fertile Soils: Volcanic ash and weathered volcanic rocks release minerals that make the soil very fertile for agriculture.
2. Geothermal Energy: Heat from the Earth’s interior can be harnessed to generate electricity.
3. Mineral Deposits: Volcanic activity can bring valuable minerals (e.g., gold, silver, copper) closer to the surface.
4. Tourism: Volcanic landscapes, hot springs, and geysers attract tourists.
5. Building Materials: Volcanic rocks like basalt and pumice are used as building materials.

Negative Effects:

1. Loss of Life and Property: Eruptions can cause widespread destruction, leading to loss of life and damage to infrastructure.
2. Climate Change: Large eruptions can release ash and gases into the atmosphere, temporarily affecting global temperatures and weather patterns.
3. Lahars (Mudflows): Volcanic ash mixing with water (rain or melted snow) can create dangerous mudflows.
4. Pyroclastic Flows: Fast-moving currents of hot gas and volcanic debris, extremely destructive.
5. Tsunamis: Underwater volcanic eruptions or collapses can generate tsunamis.
6. Air Pollution: Volcanic gases (sulfur dioxide, carbon dioxide) can cause respiratory problems and acid rain.

Illustrative Examples and Applications

1. Mount Cameroon is an example of a volcanic mountain in West Africa.
2. Dykes and sills are intrusive volcanic features, while volcanic cones and lava plateaux are extrusive features.
3. Volcanic activity may create fertile soils and useful mineral resources, but eruptions can also destroy settlements and vegetation.

Quick Revision Table

Area	Key Point
Meaning of Volcanicity	Volcanicity refers to all phenomena connected with the movement of molten rock (magma) from the Earth’s interior to the surface. It includes the…
Volcanic Processes	Volcanic activity involves several processes: Crustal Disturbances: Movements within the Earth’s crust, often related to plate tectonics, create…
Regions of Volcanic Occurrence	Volcanoes are not evenly distributed across the Earth’s surface. They are mostly found in specific zones, which include: The Pacific Ring of Fire:…
Intrusive Features or Landforms	These are landforms created when magma cools and solidifies below the Earth’s surface. They are later exposed by erosion of overlying rocks….
Extrusive Features or Landforms	These are landforms created when lava, ash, and gases erupt onto the Earth’s surface. Volcanic Cones: Hill-shaped landforms built up by layers of…
Effects of Volcanicity	Volcanic activity has both positive and negative effects on the environment and human life. Positive Effects: Fertile Soils: Volcanic ash and…

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction and Recall

Time: 4 minutes

Teaching Skill: Set Induction

Teacher’s Activity: The teacher greets the students and asks them if they have ever heard of volcanoes or seen pictures of erupting mountains. The teacher then introduces the topic "Volcanicity" by explaining that it is about the movement of molten rock from inside the Earth to the surface.

Students’ Activity: Students respond to the teacher's questions and listen attentively to the introduction.

Learning Point: Prior volcanicity knowledge.

Step 2: Explanation of Volcanicity and Processes

Time: 5 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher defines volcanicity and explains the various volcanic processes, including crustal disturbances, intrusion, extrusion, eruption, and emission, using diagrams and short video clips.

Students’ Activity: Students watch the video clips, observe the diagrams, listen to the explanations, and ask questions for clarification.

Learning Point: Volcanicity Processes concepts.

Step 3: Discussion of Volcanic Regions

Time: 5 minutes

Teaching Skill: Discussion/Map Work

Teacher’s Activity: The teacher displays a world map and guides students to identify and discuss major regions of volcanic occurrence, such as the Pacific Ring of Fire, Mid-Atlantic Ridge, Mediterranean Belt, and East African Rift Valley. Students are guided to mark these regions on their tracing paper over the world map.

Students’ Activity: Students actively participate in the discussion, locate the regions on the world map, and mark them on their tracing paper.

Learning Point: Volcanicity regions identified.

Step 4: Explanation of Intrusive Features

Time: 5 minutes

Teaching Skill: Explanation/Illustration

Teacher’s Activity: The teacher explains the formation of intrusive features or landforms (e.g., batholiths, laccoliths, lopoliths, sills, dykes) using clear diagrams and sketches. The teacher emphasizes that these features are formed underground and exposed later by erosion.

Students’ Activity: Students observe the diagrams, listen to the explanations, and take notes.

Learning Point: Intrusive Features concepts.

Step 5: Explanation of Extrusive Features

Time: 5 minutes

Teaching Skill: Explanation/Illustration

Teacher’s Activity: The teacher explains the formation of extrusive features or landforms (e.g., volcanic cones, craters, calderas, lava plateaus, geysers, hot springs) using diagrams and documentary film excerpts. Different types of volcanic cones are also discussed.

Students’ Activity: Students observe the visual aids, listen to the explanations, and ask questions.

Learning Point: Extrusive Features concepts.

Step 6: Effects of Volcanicity

Time: 5 minutes

Teaching Skill: Discussion/Questioning

Teacher’s Activity: The teacher leads a discussion on both the positive and negative effects of volcanicity, prompting students to share their ideas. The teacher ensures that key points like fertile soils, geothermal energy, mineral deposits, and destruction, loss of life, and climate impact are covered.

Students’ Activity: Students contribute to the discussion by mentioning positive and negative effects they know or have learned.

Learning Point: Effects of volcanicity.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. What is volcanicity?
2. Mention three volcanic processes.
3. List two major regions of volcanic occurrence.
4. Differentiate between intrusive and extrusive volcanic features.
5. State two positive and two negative effects of volcanicity.

Students’ Activity: Students answer orally and in writing, showing working or giving examples where the lesson requires it.

Learning Point: Volcanicity skills assessed.

Step 8: Note-Taking

Time: 8 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides students to copy the essential Board Summary on volcanicity into their notebooks, drawing attention to the key rules, examples, diagrams or distinctions already taught.

Students’ Activity: Students copy the essential notes carefully into their notebooks and correct any errors in their earlier work.

Learning Point: Volcanicity notes recorded.

Step 9: Conclusion

Time: 3 minutes

Teaching Skill: Reinforcement/Summarization

Teacher’s Activity: The teacher summarizes the main points of the lesson, reiterating the definition of volcanicity, its processes, features, and effects.

Students’ Activity: Students listen to the summary.

Learning Point: Volcanicity concepts consolidated.

Continuous Assessment/Further Study

Type: Homework / Map Work

Instruction: Complete the following tasks using the Board Summary, relevant maps or diagrams, and examples from the lesson.

1. Prepare a one-page revision note on Meaning of Volcanicity, using at least two examples from the Board Summary.
2. Draw a labelled diagram, sketch or outline map that illustrates Volcanic Processes where appropriate, and add a short explanation.
3. Construct a two-column table comparing key points from Volcanic Processes and Regions of Volcanic Occurrence.
4. Use a Nigerian, African or world example within the lesson scope to explain Intrusive Features or Landforms.
5. Write one examination-style paragraph explaining an important relationship or application in volcanicity.

Lesson Keywords

• Volcanicity – All phenomena related to the movement of molten rock from the Earth’s interior to the surface.
• Magma – Molten rock found beneath the Earth’s surface.
• Lava – Molten rock that has erupted onto the Earth’s surface.
• Intrusion – Magma cooling and solidifying within the Earth’s crust.
• Extrusion – Lava erupting and solidifying on the Earth’s surface.
• Volcano – A vent in the Earth’s crust through which lava, ash, and gases erupt.
• Crater – A bowl-shaped depression at the top of a volcano.
• Caldera – A large, basin-shaped volcanic depression formed by the collapse of a volcano.
• Geyser – A hot spring that intermittently ejects a column of hot water and steam.
• Pacific Ring of Fire – A major area in the basin of the Pacific Ocean where many earthquakes and volcanic eruptions occur.

Differentiation

For students who grasp concepts quickly, the teacher can encourage them to research specific famous volcanic eruptions and their impacts. For students who require additional support, the teacher can provide simplified diagrams and allow them to work in pairs during map activities, offering more direct guidance and simplified explanations.

Suggested Lesson Videos

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