SEA FLOOR SPREADING

TURN AND TALKWith a partner, imagine you are in a submarine. What do you think the sea floor looks like?

What do you see? Have you ever seen a picture of the sea floor or watched a video about it?

If not, predict what you think the sea floor might look like. Be prepared to share with the group.

MAP OF THE SEA FLOOR• Notice the

mountains that seem to be right in the middle of the ocean.

• What can you infer about the ocean floor based on this observation?

Mid-Ocean Ridge System

THEN AND NOWAccording to studies by geologists, the Earth has

not always looked the way it does now.

Pangaea (Greek, meaning ‘all lands’)

Positions of the continents approximately 200 million years ago

COMPARE AND CONTRAST

Positions of the continents approximately 200 million years ago

EARTH IS MADE OF PLATES

Types of PlatesDivergent - plates move away from one

another

Convergent – plates move toward one another

Transform – plates move horizontally past

one another

Paleomagnetism – the study of Earth’s magnetic field as recorded in ancient rocks

POLARITY

Earth has 2 magnetic poles, North and South.

Normal Polarity – exhibited by rocks with magnetic minerals which ‘point’ towards today’s position of the magnetic north pole.

Reversed Polarity – exhibited by rocks with minerals which ‘point’ towards today’s position of magnetic south.

SEA FLOOR SPREADING ACTIVITY

• Break into groups of 3 or 4• Label yourselves A, B, C, or DA and B-you will pull the pieces of paperC-you will use one color marker to color in the middle of the paper for normal polarity.D-you will use another color marker to color in the middle of the two papers for reversed polarity

Sea Floor Spreading Results

• Look at your sea floor map. Label the parts of normal polarity and reversed polarity.

• Label the rift zone.• Label where the oldest and youngest rocks

might be located.• Turn in your map with your names on the

back when you are finished.

Sea Floor After Normal Polarity

REVIEW

On an index card, briefly describe how the sea floor spreads. Remember to use your vocabulary words: tectonic plates, magma, divergent plates, normal and reversed polarity.

On the back of your index card write one thing you are still confused about or would like more information about.