How do convection currents form?

a. heated mantle material is less dense and rises to the top of the asthenosphereb. mantle material cools under the lithosphere, becomes more dense, and sinksc. seismic waves act like a big spoon and stir up mantle material d. both a and b are correct

Tuesday, October 23rd

Corny Joke of the DayWhat did one mountain say to the

other after the earthquake?

“It isn’t my fault”

Tier 2 PT=Tomorrow

10 pts Each

Quiz Answers

Individual and Group

Project Grades

Welcome to Ms. Evans Cheer Camp

When I say transform you

say

Slide

Transform

Transform

When I say Divergent you

say

Apart

Divergent

Divergent

When I say convergent you

say

Collide

Convergent

Convergent

Review Plate Tectonics #2Convergent Boundaries

A convergent boundary is where two plates come together, or converge. The result of the plates hitting together is called a collision.

a. Continental crust to continental

b. Continental crust to oceanic

c. Oceanic crust to oceanic

from: http://www.geo.lsa.umich.edu/~crlb/COURSES/270

a. Continental crust to continental crust

Example: India-Asia (Himalayas)

Before collision

After collision

MOUNTAINS

Indian plate (continental crust) running into Eurasian plate (continental crust)

Indian plate

Eurasian plate

Himalaya MountainsFrom space

Even the Appalachian Mountains!

Folded mountains – notice the rock layers

b. Continental &

OceanicSUBDUCTION

The process by which the

ocean floor sinks beneath a deep-ocean

trench and back into the

mantle is called

Why Does the Oceanic Crust sink below the Continental Crust?

Oceanic crust is MORE

DENSE than Continental!

• Because one plate gets pushed under another, it is

called subduction. • This is where volcanoes and

trenches form!

all from: http://www.geo.lsa.umich.edu/~crlb/COURSES/270

Volcanoes form

where a convergen

t boundary

occurs between oceanic

crust and continenta

l crust.

South American plate (continental crust) running into Nazca plate (oceanic crust)

c. Oceanic &

OceanicSUBDUCTION

Volcanoes also form where a convergent boundary occurs between oceanic crust and

oceanic crust.

Aleutian islands of Alaska are volcanoes formed by oceanic crust converging with oceanic

crust

Following volcanic islands in the Pacific Ocean can show us where oceanic crust is

being subducted by oceanic crust.

Review Plate Tectonics #3Divergent Boundaries

The place where two plates move apart or diverge is called a divergent boundary.

#1 Sea floor spreading

Can you explain this diagram!?

What causes sea floor spreading?

This is a model of sea floor spreading at a divergent boundary is called a

mid ocean ridge.

Oceanic crust diverging from oceanic crust

Did you know that the Earth’s longest mountain range is underwater and is called the mid-ocean ridge?

: www.ocean.udel.edu

The Mid-Ocean Ridge system, shown above snaking its way between the continents, is more than 56,000 kilometers (35,000 mi)

long. It circles the earth like the stitching on a baseball!

Continental crust diverging from continental

African rift valley

Iceland’s rift valley

Review Plate Tectonics #4Transform Boundaries

A transform boundary is a place where two plates slip past each other, moving in opposite directions.

San Andreas Fault in California

Let’s Watch it in action!

http://www.youtube.com/watch?v=ZxPTLmg0ZCw

WorktimeTIER 2 Reminders:

1. Make sure you are following the rubric!

2. Typed or written in blue/black ink 3. If you want me to look at it, I will! 4. Model=you should have three 5. Script=should be at least two pages 6. Let you me know if you need

help!!!!!!!!!!