Bell work week 16 Pick a science word and write the definition. Chapter 9 Tape your self assessment sheet on pg. 32 RS. Graph your post test and complete your post reflection. Clear your desk for pre-test.

Bell work week 16 Pick a science word and write the definition. Chapter 9 After bell work graph your pre-test for volcanoes and earthquakes.

Title of notes: Volcanoes Pg. 33 & 34 Goal for lesson: (write on your self assessment worksheet) I can describe a volcano.

I’ll know I’ve got it when… Learning target I can describe a volcano. Today I am… distinguishing a volcano from other land features. So that I’ll be able to… identify volcanoes. I’ll know I’ve got it when… I can describe in one sentence what a volcano is.

A Volcano is… An opening in Earth’s crust through which molten rock, gases, and ash erupt. Also, the landform that develops around this opening.

Volcano video clip https://www.youtube.com/watch?v=uZp1dNybgfc

Why Volcanoes form Volcanic Eruptions occur when magma rises to the surface. This will happen when the asthenosphere melts enough to flow. There are three things that can cause this: 1- A decrease in pressure (like at a mid-ocean ridge or rift valley) 2- An increase in temperature (like at a hot spot) 3- An increase in the amount of water in the asthenosphere (like at subduction)

Where Volcanoes Form Hot Spots Most volcanoes occur at: DIVERGENT boundaries CONVERGENT boundaries that have SUBDUCTION. Hot Spots

Volcanoes at Divergent Boundaries Decrease in pressure as plates pull apart lets magma rise. These fissure volcanoes are located at the Mid-Atlantic Ridge and the Great African Rift Valley

Volcanoes at Convergent Boundaries (Subduction) Subduction increases the amount of water in the asthenosphere, which lowers the melting temp. As the denser oceanic crust is pushed lower, it melts into magma. When continental and oceanic plates converge, a volcano forms on land. When 2 oceanic plates converge together, a volcano forms an island. Mount Hood/ Portland

Volcano- Convergent Mt St. Helens

Hot Spots We call these HOT SPOTS. Sometimes, volcanoes occur at places that aren’t plate boundaries. We call these HOT SPOTS. Hot spots are areas where hot magma rises from deep in Earth’s mantle. Magma escapes where the crust is the thinnest or weakest. It starts out solid then it melts when it reaches areas of lower pressure.

Example of Hot Spot Volcanoes that make up Hawaii.

Mount St. Helens eruption We will watch in class! https://www.youtube.com/watch?v=nXQ8HXgbD6s https://pubs.usgs.gov/gip/103/

Mount St. Helens facts Located in the Cascade Mountain range During the past 4,000 years, Mount St. Helens has erupted more frequently than any other volcano in the Cascade Range. Since 1986, snow and rock accumulating in the deep, shaded crater formed Crater Glacier, the youngest glacier on Earth.  March 20, 1980—A magnitude 4.2 earthquake signaled the reawakening of the volcano after 123 years. Morning of May 18, 1980— The largest terrestrial landslide in recorded history reduced the summit by 1,300 feet and triggered a lateral blast.   September 2004—Mount St. Helens reawakened, and it erupted continuously until January 2008.  A link in the chain of the “Ring of fire”