DO NOW Turn in Plate Tectonics Boundaries handout Pick up notes sheet and Review #10.

LOOKING BACK… Which is: Convergent? Transform? Divergent?

Divergent Plates: Rift Valleys and Mid Ocean Ridge Transform Boundaries: Offset Geology SES2. Students will understand how plate tectonics creates certain geologic features, materials, and hazards. Distinguish among types of plate tectonic settings produced by plates diverging, converging, and sliding past each other. b. Relate modern and ancient geologic features to each kind of plate tectonic setting.

PLATES, FAULTS, STRESSES AND LANDFORMS Boundaries Force Stresses Faults Landforms Convergent Destructive Compression Reverse Ocean Trenches and Mountains Transform Neutral Shear Slip-strike Offset Geology Divergent Constructive Tension Normal Rift Valleys and Mid-Ocean Ridges

DIVERGENT PLATE BOUNDARIES Plate separates. Tension stress Normal fault Landforms Created: Rift Valleys Fault-block Mountains Mid-Ocean Ridges Constructive Force – creates new plates where magma rises.

DIVERGENT BOUNDARIES: PLATES BREAK APART Magma pools up under crust. Heat trapped. Crust is thin and weak. Begins to pull apart. Fault develops as crust breaks.

DIVERGENT BOUNDARIES: PLATES BREAK APART Forms a rift. Rifts make new divergent plate boundary. Link to rift animation

BREAK UP OF PANGAEA Formed at end of Permian 225 million years ago. A rift split Pangaea from east to west during the Triassic era (200 million years ago). Created smaller continents Laurasia and Gondwanaland.

SUPERCONTINENT CYCLE Geologic cycle. Continents merge and split repeatedly. Continental collisions and break ups have occurred several times in Earth’s history.

National Geographic Video Link: The Early Earth and Plate Tectonics SUPERCONTINENT CYCLE Pangaea - 225 million years ago Gondwanaland ~ 600 million years ago Rodinia ~ 750 million to 1 billion years ago Columbia (?) ~1.8 to 1.5 billion years ago Kenorland (?) ~2.7 to ~2.1 billion years ago Ur ~3 billion years ago National Geographic Video Link: The Early Earth and Plate Tectonics

FUTURE EARTH Continents will move and change. New supercontinents will form. Notice Great Rift Valley in Africa….

DIVERGENT PLATES CREATE NEW CRUST: MID OCEAN RIDGES Oceanic plates separate. New crust in center. Crust older farther from center. Sediment builds up farther away from center. Ridge builds up around fissure.

DIVERGENT OCEAN PLATES Magma rises. Pushes out as it rises. Creates new sea floor.

DIVERGENT OCEAN PLATES Cools and moves outward from central ridge. Old crust collides with other plates and subducts.

MINERALS AT RIDGES Ocean crust is generally MAFIC rock. Heavy metals such as Iron and Manganese. Manganese nodules found on the ocean floor. Sulfur and other minerals build up at the ridge.

LANDFORMS CREATED: RIFT VALLEYS Continental plates separate. Forms depression on crust – valley. Valleys created by tectonics rather than erosion. Can create lakes, seas, hotspots and volcanoes. Valleys also called grabens.

LANDFORMS CREATED: RIFT VALLEYS Mountains: Fault-Block Few continental Rift Valleys: Great Rift Valley in Africa Rhine Rift Valley in Germany Non-Example: Grand Canyon caused by river erosion - NOT a rift valley.

PLATES, FAULTS, STRESSES AND LANDFORMS Boundaries Force Stresses Faults Landforms Convergent Destructive Compression Reverse Ocean Trenches and Mountains Transform Neutral Shear Slip-strike Offset Geology Divergent Constructive Tension Normal Rift Valleys and Mid-Ocean Ridges

TRANSFORM BOUNDARIES Plates move opposite relative to each other. Shear force. Slip-strike fault. Neither creates or destroys crust – neutral.

LANDFORM FEATURES Offset Geology Landforms displaced laterally (side to side).

EXAMPLE: SAN ANDREAS FAULT Video Link: Violent Pacific: San Andreas Fault

SOMETHING TO THINK ABOUT At what location is: Old ocean crust subducting? Magma spreading outward? New ocean crust forming? Magma rising? D B C A

ACTIVITY Cut and Paste Review #10