Script for
Volcanoes

This slideshow is designed for upper primary.  This presentation has students look at the different types of volcanoes and the rocks they produce.  It helps them understand the difference between a mountain produced by a volcano or not.

Suggested storybook:  The Fiery Slopes of Mt. Etna

Slide 1.  Eruption of Krakatau, Indonesia (background information)

·       Krakatau erupted in 1883, in one of the largest eruptions in recent time. Krakatau is an island volcano along the Indonesian arc, between the much larger islands of Sumatra and Java (each of which has many volcanoes also along the arc).

·       The volcanic dust veil that created such spectacular atmospheric effects also acted as a solar radiation filter, lowering global temperatures as much as 1.2 degree C in the year after the eruption. Temperatures did not return to normal until 1888

·       Krakatau is still active. The presently-active vent has formed a small island in the middle of the ocean-filled caldera that developed during the famous big eruption of 1883. The island is called Anak Krakatau, which means child-of-Krakatau. It is pretty much erupting all the time at a low level, but once or twice a year it has slightly larger eruptions that people notice and sometimes report in the news. None of these are anywhere near the size of the famous 1883 eruption.

·       Volcanoes are important to the evolution of earth.  It produces the mother rock which in part all planets have.   Volcanoes are the life line to have enough energy to fuse hydrogen and oxygen and produce water.  Volcanoes mean that a planet is alive for life as we know it.

 Slide 2. Key concepts. Have a discussion about each bullets to determine the level of the students/how much they know.

·       Volcanoes produce rocks called volcanic rocks.  This is a subset of igneous rocks.  All rocks originally begin their “lives” as igneous rocks.  It sometimes is referred to as the “Mother Rock.”

·       Volcanoes form different shapes. There are  many way in which you can describe volcanoes.  We will discuss  three types of volcanoes, that represent different types of formation.  Shield, cinder and composite volcanoes are the 3 types.

·       Volcanoes are associated with plate tectonics. The location of volcanoes helps us determine plate boundaries, and are major indicators of Subduction Zones.

·       We will be learning about both present and past volcanoes. The present is key to the past, the volcanic processes that operate today are the same as those that operated in the past. We gain a lot of information about past volcanoes and volcanic events by studying modern volcanoes. This will help us understand future eruptions.
 

Slide 3. Pompeii.
·       Go over story of Pompeii, a city in western Italy.   This city was covered by burning ash from a violent eruption of Mt. Vesuvius, which saved a moment in the death of the city.  Large voids in the ash were found to be the outline of people or animals that died that faithful day.

·        Archeologists cleared the almost 2 thousand years later and found the city of Pompeii.  Another nearby city, Herculean was also discovered later.  Click on left button for more details about Pompeii.

 Slide 4.   Where does Magma come from?

·       This is a series of slides that you can use depending on age of students.  Key is for students to know that the molten rock (magma) comes from the upper mantle, and not deep inside the earth. 

·       Explain the cross section of the Earth. Use both the slides and the model of Earth to show and describe the layers.   The layers were described prior to understanding the mechanisms of Plate Tectonics.

Slide 5.

·       The center of the Earth is composed of the Inner core.  Through seismic data geologists have interpreted the data as it is made of solid iron and nickel.  Thought to have accreted through time.  We cannot directly drill into the core, so we do not have direct evidence. 

·       The inner core is surrounded by the outer core. It is thicker than the inner core and is composed of liquid nickel and iron. Liquid as defined as molecules that flow, but the flow is not like water. Remember this is under extreme pressure.

·       The Mantle is the next thick layer. It is primarily solid, but is still very hot. It is rich in silica.

·       The crust is the outermost layer of the Earth. It is also the thinnest layer. This is the part of the earth that is composed of many different types of rock.

So where does magma come from?  The upper mantle and crust.

Slide 6.

·       Ask the students what layer of the Earth produces magma? Many will think magma comes from the core. Magma is produced in the upper mantle and crust. This is given a designation of “asthenosphere.”

·       Ask the students how the magma reaches the surface. It is through volcanoes! Molten rock is less dense and rises through the crust.

·       As Plate Tectonics became accepted to explain earthquakes and volcanoes, the system of “spheres” evolved.   Hydrosphere” is the sphere of water; “Atmosphere” is the sphere of air; “Lithosphere” is the sphere of rock; and the “Asthenosphere” is the sphere of  fluid crust and upper mantle.

·       The Lithosphere is a combination of the crust and the outermost part of the mantle. It is hard and brittle. The thickness of the lithosphere is the thickness of the tectonic plates.

·       The Asthenosphere is the portion of the mantle below the lithosphere. The asthenosphere is a little squishy, like silly putty and can move. The lithosphere floats on top of the asthenosphere and the tectonic plates move as the asthenosphere moves. You can use a conveyor belt or a moving walkway as an example if the students need a little help understanding this concept.

·       Now describe basic tectonics/interactions between tectonic plates based on how they move. Using your hands to demonstrate this is helpful.

·       Divergence – This is when two plates move away from each other (move hands away from each other). Divergence usually happens in the middle of the oceans. Sometimes divergence can cause landforms to collide.

·       Convergence – This is when two plates move toward each other (bring hands together with fingers facing each other). Ask students what they think can happen to the plates when they come together. The plates will collide and can form mountains like the Alps or Himalayas, and volcanoes (bring fingers up to demonstrate mountains).

The collision can also result in subduction, one plate (ocean) sinks under the other (continent) (slide one hand below the other). Subduction can result in mountain and volcano formation. The volcanoes form when the ocean plate starts to melt beneath the continent plate.

Slide 7.

·       Volcanoes help us define and understand where the tectonic plates boundaries are located. Plate movement often results in the formation of volcanoes. When you look at a map with all the volcanoes you start to see a pattern, these are the outlines of the plates. Point out the ring of fire. This large region is very active tectonically, it has many volcanoes (hence “ring of fire”).

·       Point out Hawaii, it is the dot in the middle of the Pacific Ocean.  Depending on the level of the students you can describe Hot Spots. Most volcanoes occur at the boundaries of tectonic plates, but sometimes there are very, very hot areas of the mantle and they can burn right through the crust in the middle of a plate!

Slide 8.  

·       This Hawaiian eruption shows gas and ash being released violently.  Notice the red is molten lava, while the dark is formation of rock, mainly obsidian.    Point out that when some volcanoes erupt it tends to be very violent and noisy.   Other volcanoes can be slow and quiet. 

·       Have the students imagine that if a large amount of lava is blown into the atmosphere, up to a mile, a “volcanic bomb”  will fall to earth with such force it acts like a bomb.

Slide 9.

Allow animation to run of the volcano/igneous rock production to run. Go over what is happening and expand if necessary. Repeat animation until students understand the difference between “plutonic” and “volcanic.”

·       All igneous rocks start as molten/liquid magma below surface. During an eruption some of that magma erupts at the surface. When magma comes to the surface it is called lava. Lava makes types of igneous rocks called volcanic rocks. These rocks cooled quickly and have small minerals.

Slide 10. See what students know about the parts of the volcano.  See if they can identify parts correctly.

·       Magma chamber (A).  The depth of magma chambers varies depending on the area and type.  For example, Iceland average depth is 12.4 miles (20 km); Hawaii is about 2 miles (3.5 km); and Yellowstone has several chambers ranging in dept from 5-50 km

·       Vent (B)  Vents are openings where lava flows from a stream of molten lava as it rises.  Note there are many types and sizes of vents, depending on type of volcano.  Definitions vary depending on the type of audience.

·       Steam, gas, dust  (C)  Steam is usually water, but also hydrogen sulfide gas and other gases are emitted which are generally called gas.  Ash would be find particles  Volcanic bombs (a type of volcanic rock) (D)  Lava under pressure that is hurled upward and starts cooling as it comes back to earth.  Usually has an oval shape.

·       Lava Flow  (F) Liquid rock that moves according to gravity.  Many different types of flows can be created.

Slide 11. Play animation. Reiterate volcanic rock formation and the types of volcanic rocks (plutonic and volcanic). Show samples of the different types of igneous rocks using samples at the front of the table.

·       Magma that cools inside of volcanic chambers is called Gabbro. Gabbro is dark and has large crystals that you can see without magnification.

·       Several types of volcanic igneous rocks are produced during an eruption.

·       The outside of a lave flow cools the fastest. The type of volcanic rock that forms here is obsidian. It is shiny and generally black. It cools so fast that you cannot see the crystals.

·       The inside of a lava flows cools a bit slower than the outside of the lava flow, but still cools faster than the magma in the chamber. The type of volcanic rock that is produced here is basalt. Basalt is dull and black; you cannot see crystals.

·       When lava mixes with volcanic gasses it forms pumice. Pumice is light in weight and porous (from all of the gas bubbles escaping). Think of pumice like the foam that forms on top of a soda when you shake it. That soda foam is a mix of the soda and gasses, just like pumice is a mixture of liquid lava and gases.

Slide 12.  Basalt/Gabbro

·       If the magma is chemical low silica it will produce darker minerals or what geologist call mafic. So the lava and magma are chemically similar. The plutonic rock is dark and called Gabbro with large minerals of hornblende and pyroxene.  The volcanic rock is also dark with small minerals and is called basalt. 

Slide 13.  Granite and Rhyolite 

·       If the magma is chemically high in silica it will produce minerals like quartz and feldspars which are light in color.  These rocks are groups as continental rocks, since they are also less dense and form large land masses.  So the magma would be granitic and the lava would be rhyolitic.

Slide 14: Types of volcanoes

Now we will be discussing the three different types of volcanoes.  Vulcanologist have many more specific groups, these are 3 basic ones that form rocks. These pictures depict the types, Composite (Mt. St. Helens, top left; Etna, top right; Mt. Vesuvius, bottom left), Shield (Hawaii, center bottom), and Cinder (Mauna Kea, center top; Paricutin, Mexico, bottom left). You can ask the students to Guess the volcanoes. Give them clues for each picture including the location.

 Slide Composite Volcanoes  A-F
These volcanoes are composed of alternating layers of lava flows and ash flows. Quickly go over parts, but more important to see photographs and videos. Each of the slides with their location.  

·       Ash (A)

·       Ash Flow (B)

·       Lava Flow (C)

·       Sill (D)

·       Dyke (E)

·       Lava (F)

·       Flank eruption G

 Pictures include:

Mt Fuji, Japan

Mt. Lassen, California USA

Mt Etna, Sicily, Italy

Mt. St Helen, Washington, USA  Video of eruption in 1981

Mt. Vesuvius, Naples, Italy

Slide Shield Volcanoes A-D

these volcanoes are composed almost entirely of lava flows. Repeat exercise from previous slide.  

Belknap, Oregon, US
Hawaii
Hawaii (Pahoehoe with video)
Magma chamber (A)

·       Lava Flow (B)

·       Flank eruption (C)

·       Summit Caldera (D)

·       Central Vent E

Slide Cinder Cone Volcanoes

These volcanoes are composed entirely out of ash/cinder flows. They are essentially a big pile of cinders/scoria. Repeat exercise from previous slide.

·       Ash (A)

·       Crater (B)

·       Cinder Beds (C)

·       Vent (D)

 Slide 15.  Importance of Volcanoes

Volcanoes produce “Mother Magma” and tell us if a planet is “alive”  First slide goes over 6 points of why volcanoes are important.

 Slide 16. Water production

Over 4.5 billion years, the amount of water that has been produced by volcanoes has actually given us the water that we have on Earth .  The internal energy produced can unite Hydrogen and Oxygen, forming water.  It took almost 1 billion years before water accumulated on Earth.  This water became the important ingredient to supporting life as we know it.

 Slide 17. Atmospheric cooling

 Large eruptions can cause a change in temperature. One of the shorter-term benefits could be observed with recent large eruptions including 1991’s Pinatubo eruption in the Philippines and 1982’s El Chichón eruption in Mexico, which both exploded ash and sulfur gas into the stratosphere.  They reduced the temperature by about half a degree Celsius. 

The sulfur gas combines with water in the atmosphere, creating microscopic droplets that can stay in the atmosphere for years. The effect of those aerosol droplets is cooling the lowest level of the atmosphere, which is the level in which we live and breathe.

(Pinatubo, Philippines, 1991)

 Slide 18. Land formation

The Big Island of Hawaii with Kilauea’s current eruption, as lava is pouring into the ocean and creating new land.  All of the land in the Hawaiian Islands was created this way. This land formation can take thousands of years.

Iceland is also a good example of building land masses.  Bardarbunga eruption in 2017 disrupted flight around Iceland

Slide 19. Fertile land

Fertile soil is another advantage of volcanic activity.  Ash mixed with other soil provides elements that are small enough for plants to use.  Grape vines are noted for liking ash rich soil in Italy and Napa County in California.

Volcanic soil in Lanzarote, Spain with protection from the wind.

Hot springs and geothermal energy are additional benefits. People use geothermal energy in places like Iceland, Yellowstone Natural Park, and New Zealand.  Typically called “hot springs.”  The most active geothermal resources are normally found along major plate boundaries where volcanoes and earthquakes occur.

The Geysers Thermal Field in California (right)

 Slide 21. Building materials

Volcanoes also provide a lot of building materials. Volcanic material can be made into blocks, and lot of the materials are mined around the world.  “Cinder” blocks come from the cinders of volcanoes.

Early civilizations used bricks cut from volcanoes.

Slide 22 – Quiz. This quiz is optional, it asks students to pick out which pictures represent  volcanoes and which represent mountains.  Many times students think that a mountain is a volcano.  Remind them that the Earth has other focuses (plate tectonics) that causes uplift.