• rigid, moving pieces that make up te earth's surface

• theory of formation and movement of rigid pieces of the Earth's crust, called plates

• Conviction is the flow of heated liquids and gasses in a circular motion
• the molten rock (Magma) moves through the crust layer called the Lithosphere

• a fossil found along the east coast of North America and British Isles
• provides evidence that North America and British Isles were once part of the same continent

State 4 (or more) facts about the Lithosphere

• forms the outer shell of Earth
• extends 100km below the surface
• rigid, but broken into plates that move
• composed mainly of igneous rock called basalt
• continents tend to be composed of less dense granite
• as lithospheric plates move apart or together they carry continents with them 

• layer below lithosphere
• part of the Mantle
• similar in composition to lithosphere
• partly liquid form, flows very slowly in convection currents
• rising currents bring up new material
• cooler, denser, sinking convection currents pull plates apart

• theory : that continents were previously together and have drifted apart
• theory : that continents continue to drift on the Earth's surface
• proposed by German scientist Alfred Wagner

• places where one plate moves relative to another plate
• earthquakes and volcanoes are located along these boundaries

• igneous rocks contain minerals that are magnetic 
•  the rocks provide a record of the movement direction of the earth's magnetic poles
• the magnetic poles have reversed 4 times in the last 4 million years
• where lithospheric plates move apart, polarity reversals occur in bands parallel to and on opposite sides of plate boundaries

• at areas of expansion
• (since the convection currents brign up fresh magma that has not cooled near the Earth's surface yet)

• the spreading center where two lithospheric plates are moving apart and new lithosphere is formed
• most diverging boundaries have mid-ocean ridges
• Diverge = to move apart

• the boundary between the lithospheric plates and the place where new rock forms, pushing older oceanic crust aside
• Example: the deep valley along the length of the Mid Atlantic Ridge

• separates:
• North American Plate from the Eurasian Plate
• South American Plate from the African Plate

• a break or crack in the Earth's crust along which movement has occurred

• areas where the lithospheric plates are sliding past each other
• Ie. San Andreas Fault in California

• converging = coming together
• a boundary that forms when two plates come together or converge
• the plates may be moving in opposite directions or one plate may be moving faster behind a plate moving in the same diredtion

• type of converging boundary formed when 2 continents collide, are "welded" together by massive heat/ pressure into  single, larger plate
• ie. Indian sub-continent is pushing into  Aisian continent
• collision causes lithosphere at boundary to be pushed upward: mountain range
• ie. Himilayas between India/ China, highest mountain range in world today

• converging boundary plate where one plate plunges beneath another over-riding plate
• ie. Juan de Fuca, off the coast of BC

• deep sea trenches that form between plates 
• volcanic islands that form along the over-riding plate
• earthquakes along the subduction boundaries originate deeper in the interior of the earth

the ancient core of a continent

• usually the oldest, most altered rodks on the continent
• North America: Canadian Shield is an exposed part of the Craton
• a continent can grow in size by having material added to it by: deep sea and river sediments, volcanic rock
• thin skinned thrusting
• attaching terranes

• Sediment is not extra created material, but when it is relocated and deposited along continental margins it adds to the land mass above sea level (ie Fraser River Delta)
• These sediments are NOT part of the active plate boundaries.

• the pushing of thin, horizontal sheets of rock from continental margins over great distances along nearly level falut surfaces
• this is thought to occur in many of the world's mountain ranges (ie the Appalachian Mountains of Eastern USA)

a large block of lithosphere that has been:

• moved, often thousands of kilometers,
• and attached to the edge of a continent

• each terrrane is bounded on all sides by major faults
• rocks and fossils in each terrane do NOT match those of neighbouring terranes
• Magnetic polarity of each terrane does not match it's neighbour
• thought to be the primary method of continental growth in western North America ( ie Cache Creek in BC is thought to have come from Japan and parts of Asia)