VOLCANOES CHANGE THE LANDSCAPE

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LESSON 19

• VOLCANOES CHANGE THE LANDSCAPE

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OBJECTIVES

• Model the movement of molten rock through
  fractures in the lithosphere, over the earths
  surface, and underwater.
• Devise working definitions for the words magma
  and lava.
• Identify in photographs landforms created by
  molten rocks.

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Reflections

• A. Were there any signs in the soil that magma
  was moving under the ground?
• The soil cracked and bulged when the model magma
  moved beneath it. (Fig. 19.7)
• B. How does rising magma affect land with no
  hard rock above it?
• A mound can form in the land. Fractures can also
  form in the overlying land. (Fig. 19.1 19.4)

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• C. What happened when the room-temperature model
  magma reached the surface of the soil?
• Because the room-temperature magma did not flow
  easily, it most likely formed a dome-shaped
  structure when it surfaced. (Fig. 19.5)
• D. How did the flow of the room-temperature
  model magma differ from the flow of the heated
  model magma?
• The magma was runny (less viscous) at higher
  temperatures. Heat caused the substance to flow
  more freely across the soils surface. (Fig.
  19.6)

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• E. What happened to the soil when you drained
  the heated magma from it?
• The model magma retreated from the soil, causing
  the soil to collapse into a bowl-shaped
  depression. (Fig. 19.8)
• F. What did the hole in the bottom of the
  plastic container of soil represent?
• The vent in a volcano

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GLOSSARY - LESSON 19

• ASH - FINE FRAGMENTS OF ROCK
• LAHAR - A MUDFLOW THAT HAPPENS WHEN RAIN FALLS
  THROUGH CLOUDS OF ASH OR WHEN RIVERS BECOME
  CHOKED WITH FALLING VOLCANIC DEBRIS.
• TSUNAMI - A LARGE SEA WAVE USUALLY BROUGHT ON BY
  UNDERWATER EARTHQUAKES.

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• BASALT - A NATURAL PRODUCT WHICH FORMS FROM
  COOLED LAVA AND MAKES UP MUCH OF THE SEAFLOOR.
  RAW MATERIAL USED FOR CLEANING AGENTS.
• OBSIDIAN - VOLCANIC GLASS FORMED FROM COOLED
  LAVA. BREAKS WITH A CURVED FRACTURE.
• LAVA PILLOWS - UNDERWATER BALLOON-SHAPED MOUNDS
  OF LAVA.

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• LAVA DOME - THE BULBOUS, STEEP-SIDED DOME FORMED
  AT THE TOP OF A VOLCANO WHEN THICK RELATIVELY
  COLD LAVA COMES OUT OF A VOLCANIC VENT.
• LAVA FLOW - LAVA THAT IS RUNNY AND FLOWS QUICKLY
  OVER THE SURFACE OF THE EARTH AND COVERS A WIDE
  AREA.
• CALDERA - A LARGE, STEEP-SIDED CIRCULAR OR OVAL
  VOLCANIC DEPRESSION.

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• CRATER - SMALLER CIRCULAR DEPRESSIONS CREATED
  PRIMARILY BY EXPLODING ROCK DURING ERUPTIONS.
• HOT SPOT - A LOCALIZED ZONE OF MELTING IN THE
  MANTLE UNDER A PLATE.
• LAVA - MAGMA THAT ERUPTED TO THE EARTHS SURFACE.
• MAGMA - MOLTEN MATERIAL INSIDE THE EARTH.
• VOLCANOLOGIST - A SCIENTIST WHO STUDIES VOLCANIC
  ACTIVITY.

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INQUIRY 19.2 INVESTIGATING LAVA NEW LANDFORMS

• PROBLEM Why and how do you think rock melts?

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THINK ABOUT IT.

• Collect the tote tray of materials.
• Each tote tray should contain..
• 1 block of wax
• 2 hand lenses
• 1 index card
• 1 roll of waxed paper
• 1 beaker
• Masking tape
• Examine the block of wax with the hand lens.
• What are its properties? (size, shape, color,
  and odor)

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WHAT IF..

• IF YOU HEATED THE WAX, WHAT WOULD HAPPEN?
• LOOK AT THE HEATED WAX. WHAT ARE ITS PROPERTIES
  NOW?
• HOW ARE THEY THE SAME AS THE PROPERTIES OF THE
  SOLID WAX?
• HOW ARE THEY DIFFERENT?

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HYPOTHESIS

• 3. RECORD IN YOUR NOTEBOOK What do you
  think will happen?
• I predict that the melted wax will _____________
  on a flat surface.
• I predict that the melted wax will
  _______________ on a sloped surface.

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DESIGN A TEST

• IF WE WANTED TO MODEL THE BEHAVIOR OF HOT LAVA AS
  IT FLOWS ON LAND AND WHAT HAPPENS WHEN IT COMES
  IN CONTACT WITH COLD WATER, HOW WOULD WE DESIGN A
  TEST?

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SAFETY FIRST.

• BE VERY CAREFUL WITH THE HOT WAX. Keep the lid
  on the container until you are ready to use the
  wax. DO NOT PUT YOUR FINGER INTO THE HOT WAX!
• WEAR SAFETY GOGGLES.
• NO WALKING AROUND WHILE THE HOT WAX IS IN USE.
  RAISE YOUR HAND IF YOU NEED SOMETHING. WE WILL
  COME TO YOU.

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PROCEDURE

• 1. CREATE A SLOPE USING THE LID OF YOUR TOTE
  TRAY.
• 2. COVER THE SLOPE WITH A SHEET OF WAXED PAPER.
  TAPE THE TOP EDGES TO SECURE IT. BE SURE THE
  WAXED PAPER EXTENDS PAST THE LID ABOUT 10 INCHES
  ONTO THE TABLE.

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• 4. POUR ¼ OF THE CONTAINER OF HOT WAX ON THE
  FLAT WAXED PAPER. OBSERVE AND RECORD.
• 5. POUR ¼ OF THE CONTAINER OF HOT WAX ON THE
  SLOPED SURFACE. OBSERVE AND RECORD.
• 6. WAIT 5-10 SECONDS. POUR ¼ OF THE HOT WAX
  ONTO THE SAME SLOPED AREA OF THE WAXED PAPER.
• 7. WAIT 5-10 SECONDS AND POUR TH FINAL ¼ OF THE
  HOT WAX ONTO THE SAME SLOPING AREA OF THE WAXED
  PAPER.

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• 8. GET A 2ND CONTAINER OF HOT AND 200 Ml of cold
  wter.
• 9. PLACE THE WHITE INDEX CARD BEHIND THE BEAKER.
• 10. QUICKLY POUR THE ENTIRE CONTAINER OF WAX INTO
  THE BEAKER OF COLD WATER. WAIT FOR SEVERAL
  MINUTES. RECORD YOUR OBSERVATIONS IN YOUR
  NOTEBOOK.
• 11. AFTER SEVERAL MINUTES, REMOVE THE WAX FROM
  THE BEAKER. TURN IT UPRIGHT. DRAW A PICTURE OF
  WHT HAPPENED TO THE UNDERSEA LAVA.

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CLEAN UP

• ONE PERSON FROM EACH TABLE NEEDS TO COLLECT THE
  LEFTOVER SOLID WAX. YOU MAY PEEL IT OFF OF THE
  WAXED PAPER. RETURN IT TO ONE OF THE TEACHERS.
• ONE PERSON NEEDS TO POUR OUT THE WATER AND GET
  FRESH ICE WATER FOR THE NEXT CLASS.
• ONE PERSON NEEDS TO WIPE OUT THE TOTE TRAY AND
  COLLECT THE MATERIALS.
• ONE PERSON NEEDS TO WIPE OFF THE TABLE.

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REFLECTIONS 19.2

• 1. DESCRIBE THE MOVEMENT OF THE MELTED WAX ON
  THE SLOPE.
• The lava was runny and went down the slope in
  streams. More viscous wax tended to go down the
  slope in one stream.
• 2. HOW DID THE MOVEMENT DIFFER FROM THE MOVEMENT
  ON THE FLAT PART OF THE WAXED PAPER?
• It slowed down and puddled down at the bottom on
  the flat part.

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• 3. DESCRIBE THE TEXTURE OF THE COOLED WAX.
• The texture was smooth and waxy. It felt hilly
  as more layers were added.
• 4. HOW DID THE BEHAVIOR OF THE COOLING WAX ON
  THE WAXED PAPER COMPARE WITH ITS BEHAVIOR IN THE
  WATER?
• In the cold water, the lava made lava pillows
  because it cooled off immediately. On the waxed
  paper, it ran in streams for awhile.

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• 5. HOW DO YOU THINK LAVA FORMS ROCK?
• Lava reaches the surface, cools, and hardens to
  form igneous rock.
• 6. HOW DO YOU THINK VOLCANIC MOUNTAINS (SUCH AS
  MT. ST. HELENS) AND VOLCANIC ISLANDS (SUCH AS
  HAWAII) FORM?
• Over time the buildup of cooled volcanic rock
  forms mountains on land. The Hawaiian Island
  were formed from hot spots and the plates moving
  over them in the ocean.

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• 7. UNDER WHAT CIRCUMSTANCES DO YOU THINK LAVA
  FLOWS INTO THE OCEAN?
• Lava can flow into the ocean as runoff from land,
  or it can erupt into the ocean along undersea
  ridges in the ocean floor.
• 8. WHAT HAPPENS TO LAVA WHEN IT FLOWS INTO THE
  OCEAN OR ERUPTS ONTO THE OCEAN FLOOR?
• New landforms called pillow lava, form when lava
  cools quickly in cool ocean water.