Geology                     Natural Science 1003

Topic 7  Igneous processes

Primary goals

• Describe the processes that create magma.
• Describe how magma forms into igneous rocks.
• Describe volcanic eruptions, including lava flows and pyroclastics.
• Identify plutonic and volcanic landforms and describe how they form
• Be able to draw landforms, recognize them in an image, list their characteristics, explain how they form, compare them to similar features, and describe their relationship to related physical features

Topics

7.1  What affects the melting point of rock?  

• Relationship: How does mineral composition affect the melting point of rock?

• Story: What evidence do we have that the Earth was warmer inside in the past?

• Relationship: How does pressure affect the melting point of rock?

• Relationship: How does water affect the melting point of rock?

7.2  At what geologic features does rock melt to become magma?  

• Process: Magma formation by pressure-release melting at divergent plate boundaries and hot spots

• Process: Magma formation at subduction zones

• Question: What geologic features cause volcanoes?

7.3  How do different igneous rocks form?  

• Process: Partial melting

• Process: Partial crystallization

• Analytical: be able to determine which minerals in a rock will be solid and which will be molten depending on the minerals' melting points and on the rock temp

• Process: How does continental crust form?

• Terms: basaltic magma; granitic magma; andesitic magma

• Terms: magma chamber; xenolith

7.4  Magma of volcanic eruptions  

• Term: viscosity; viscous

• Relationship: How does temperature affect the viscosity of magma?

• Relationship: How does the amount of silica affect the viscosity of magma?

• Analytical: Which is more viscous, and why? basaltic magma or granitic magma?

• Analytical: Why are basaltic magmas more likely to get to the surface than granitic magmas?

7.5  Volcanic eruptions  

• Story: Typical volcanic eruption

• Relationship: How does the amount of dissolved gases generally affect the explosiveness of a volcanic eruption?

• Compare: the thickness, size, and speed of basaltic, andesitic, and granitic lava flows. Explain the differences.

• Compare: pahoehoe lava and aa lava

• Story: How does pillow lava form?

• Story: How do columnar joints form?

• Terms: pyroclastics; ash; lapilli; bomb

• Relationship: How does the thickness of the pyroclastic fall vary as you go farther away from the volcano? Why?

• Terms: pyroclastic flow; tuff; lahar

7.6   Types of volcanoes  

• Terms: shield volcano; cinder cone volcano; composite volcano; landform

7.7  Other volcanic landforms  

• Terms: crater; caldera; lava dome; fissure eruption; basalt plateau

7.8  Plutonic landforms  

• Terms: pluton; sill; dike; batholith

• Process: How are plutons formed?

• Process: If plutons form underground, how do they get exposed at the surface?

• Process: How are sills and dikes formed?

• Analytical: How are dikes and sills similar? Different?

Topic resources for students

Entire topic

• Prof. Nelson volcanoes notes

• Geology Class

Links for further interest

Entire topic

• Recent news
  --Volcano Live (THE volcano site)
  --Volcano Discovery
  --Michigan Tech Volcanoes page
• Photos
  --from NOAA--many are spectacular!
  --photos from Hawaii
• United States volcanic features
  --Alaska Volcanoes Observatory
  --Capulin Volcano National Monument
  --Cascades Volcano Observatory
  --Hawaii Volcanoes National Park
  --Hawaiian Volcano Observatory
  --Lassen Volcanic National Park
  --Lava Beds National Monument, California
  --Long Valley, California area
  --Mt. St. Helens
  --Red Mountain Volcano--cinder cone in Arizona
  --Yellowstone Volcano Observatory
• The Siberian Traps--the largest volcanic eruption in Earth history (that we know of)

7.5  Volcanic eruptions

• videos of stepping on lava  
  --short    
  --1 min
• videos of pillow lava   
  --short video 30 secs     
  --long
  --What they look like after a long time    1 min video
• videos columnar joints
  --columnar good    3 min
  --blooper
  --video from Arizona   1 min
  --another good video Iceland   1 min
  --flyover video  3 min
• videos pyroclastic flows     
  --Japan       
  --sinabung
• video inside of a volcano    3 min
• lava dome collapse of Unzen volcano in Japan and subsequent pyroclastic flow
• Detailed description of magma composition and explosiveness of volcanoes
• Description of aa lava in the Galapagos Islands
• description of pyroclastic flow from Michigan Tech
• photos of pyroclastics and pyroclastic flow from Japan
• Darwin Volcanic Ash Advisory Centre--Australia
• Eruptive history of the Higashi Izu monogenetic volcano field
• Inspiration for Mary Shelley's Frankenstein

7.6  Types of volcanoes

• Shield volcano on Mars

7.7  Other volcanic landforms

• Tweed volcano caldera, Australia
• Mt. St. Helens lava dome
• skiing at the lava dome at Mt. St. Helens
• nice description of lava domes from South Dakota State U....check out thermal map of Mt. St. Helens dome

7.8  Plutonic landforms