Presentation on theme: "VOLCANOES VOLCANOES CHAPTER 3 VOLCANOES. OBJECTIVE AND STARTER Objective: Today you will learn about volcanoes and why they form. Starter-KWL Chart K(What."— Presentation transcript:
VOLCANOES VOLCANOES CHAPTER 3 VOLCANOES
OBJECTIVE AND STARTER Objective: Today you will learn about volcanoes and why they form. Starter-KWL Chart K(What you Know about Volcanoes W (What you want to learn about Volcanoes) L (What you learned about volcanoes)
Background Information Have you ever seen a volcano? What was happening? Iceland at Night
Volcano A weak spot in the crust where molten material or magma comes to the surface.
Where are they found?
Ring of Fire Many volcanoes rim the Pacific Ocean. A major volcanic belt is cause by areas of subduction of the Earth’s crust.
Island Arc A curved chain of volcanic islands. They form in the overriding tectonic plates of subduction zones as the result of rising melt from the down-going plate
Converging Oceanic plates can cause volcanoes too!
Divergent Boundaries can form volcanoes at the mid-ocean ridge
Hot Spot An area where material from deep within the mantle rises then melts, forming magma.
M Magma text pages A molten mixture of rock forming substances, gases, and water from the mantle. Characteristics of Magma Depends on dissolved gases Temperature Silica content
Volcanic Activity Text pgs
Rock Types High in silica Light-colored and slow (too sticky) Examples: Rhyolite Pumice Obsidian Low in silica Dark colored and flows easily Basalt can sometimes form these six- sided columns seen below
Lava When magma reaches the surface. Text pg.97 Examples of lava types Aa
Volcanic Eruption Text pgs
STARTER Starter-Why do volcanoes form? What happens after a volcanic eruption.
Background Information What does lava look like when it comes out of a volcano? What else comes out of the volcano?
Magma Chamber A pocket below the volcano where magma is collected.
Pyroclastic Flow A type of explosive eruption that hurls out a mix of hot gases, ash, cinders, and effects of a bomb.
Dormant A volcano that is still and active and will awaken in the future.
Extinct A dead volcano that will no longer erupt. Volcano is declared extinct after 100 years of no eruptions.
Geyser A fountain of water and steam that erupts from the ground. Water is heated by hot rocks near magma pockets. Geyser releases pressure from superheated water as it erupts.
Parts of a VOLCANO pipe Magma chamber
VOLCANIC LANDFORMS VOLCANIC LANDFORMS
OBJECTIVE Objective: Today you will learn about landforms that are created by volcanoes.
Three Types of Volcanoes “How do they get their names?” Cinder ConeComposite Shield
What kinds of lava are connected with volcano type
Background Information What shape is a volcano? Are all volcanoes shaped like this?
Shield volcano Usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they eruptfluid warrior's shield
Cinder Cone A steep hill like volcano that slopes steeply.
Composite (Strato-) Volcano A volcano built up by many layers (strata) of hardened lava pumice and volcanic ash.
Caldera The huge hole left by a volcanic mountain.
Volcanic Neck It looks like a giant tooth stuck in the ground. Forms when magma hardens a volcano’s pipe.
Dome Mountain - other smaller bodies of magma can create dome mountains which form with rising magma being blocked by horizontal layers of rock. The magma pushes the layers to bend upward into a dome shape. Eventually the rock above the dome wears away, leaving it exposed. One example is the Black Hills in South Dakota.
Other Landforms from Volcanoes
Dikes, Sills, Batholiths A dike is when magma forces itself across rock layers while magma that squeezes between layers of rock is called a sill. Batholiths are a mass of rock that has been formed when a large body of magma cools inside the crust.