Bell Work: 11/1/11

Please write the question, answer, and explain why you chose that

answer (justify).

Objectives

• Differentiate among the characteristics of the earth’s three layers. (SPI 0707.7.4)

• Recognize that lithospheric plates on the scale of continents and oceans continually move at rates of centimeters per year. (SPI 0707.7.5)

Think, Pair, Share …Come up with an explanation to the

following question, pair up with your elbow partner, & share:

•How do we know so much about the mantle and the core?

From our discussion…• How do we know so much about

the mantle and the core?• Seismic waves, or vibrations

produced from earthquakes, travel at different speeds through the Earth. Their speed depends on the density and composition of the material they pass through.

• Traveling through a solid will go faster than through a liquid.

Restless Continents• Look at pg. 400!• In the early 1900s, ___________ ___________

wrote about his hypothesis of ____________ ______.

• Continental drift is the hypothesis that states that the _____________ once formed a single ______________, broke up, and drifted to their present locations.

• Continental drift also explained why __________ of the same plant and animal species are found on continents that are on different sides of the Atlantic Ocean.

Alfred Wegenercontinental

drift

continentslandmass

fossils

Pangaea

• Wegener thought that all of the present continents were once __________ in a single, huge continent called ______________.

• Pangaea is Greek for ______________.

joined

Pangaea

“all earth”

You try it!

Make Pangaea with the pieces of continents at

your group.

Challenging Question…

Think, Pair, Share …• Based on what you know about

tectonic plates, how would you prove Wegener’s theory to be true?

Tracking Tectonic Plate Motion• Scientist use a system of satellites

called global positioning system or GPS.• Radio signals are continuously beamed

from satellites to GPS ground stations, which record the exact distance between the satellites and the ground stations.

• Over time, these distances change slightly.

• The movement is measured in centimeters per year.

Events associated with movements of earth’s major plates:• Sea-floor spreading• Mountain building• Earthquakes• Volcanoes

Sea-Floor Spreading• ____________ __________, or underwater

mountain chains, are where ____________ ___________ takes place.

• Sea-floor spreading is the process by which new oceanic ____________________ forms as __________ rises toward the surface and solidifies.

• As ___________ __________ move away from each other, the sea floor spreads apart and magma fills the gap.

Mid-ocean ridges

Sea-floor spreading

Lithosphere (or crust)magma

tectonic plates

Draw a picture of the sea floor spreading.

Mountain Building

• ______________ exist because tectonic plates are continually ______________ around and ___________ with one another.

• The Andes Mountains in South America formed where two tectonic plates converge or collide.

• When tectonic plates undergo ________________ or ____________, they can form mountains in several ways.

Mountainsmoving

colliding

compression tension

3 types of mountains• Folded Mountains- form when rock layers are

_______________ together and pushed ___________.• Example: Appalachian Mountains

• Fault-Block Mountains- form when tectonic forces put ___________on the Earth’s crust causing large blocks of the Earth’s crust to_________ _________.• Example: Tetons in Wyoming

• Volcanic Mountains- form when _________ rises to the Earth’s surface and erupts.• Most of the world’s major volcanic mountains are

located at convergent boundaries where oceanic crust sinks into the asthenosphere at subduction zones

• Example: Mount St. Helens

tension

squeezed

downdrop

upward

magma

Draw a picture

Draw a picture pg. 413

Draw a picture

Earthquakes• The study of earthquakes is called ________________.• Most earthquakes take place near the edges of

__________ ___________.• As tectonic plates push, pull, or slip past each

other, stress increases along breaks in the Earth’s crust, or ___________.

• In response to this stress, rock in the plates _______________.

• __________ _______________ leads to earthquakes.• It’s like a stretched rubber band, you can only

stretch rock so far before it breaks. When the rock breaks, it releases ________________.

• This energy is released in the form of seismic waves.

seismology

tectonic

faults

plates

deformsElastic deformation

energy

Volcanoes• Tectonic plate boundaries are likely places for

_____________ to form.• ________ _________ _____ _________, which are

plate boundaries surrounding the Pacific Ocean, contains nearly _____ of the world’s active volcanoes.

• About _____ of active volcanoes on land form where plates ______________, and about ______ form where plates ____________.

• At these plate boundaries it is possible for _____________ to form and travel to the surface.

volcanoes

The Ring of Fire

75%

15%

80%collide

separate

magma

Draw a picture of both types of volcano formations. Use pages 464-465.

Let’s Review…

3-2-1 Reflection• 3 things that I learned…

• 2 questions I have…

• 1 way I can relate today’s lesson to my daily life…