Chapter 10 Flashcards
Wegener’s theory of continential drift.
The theory states that the continents were once bound, as a single continent. (Pangaea) (10.1)
Observations of Wegener which proved his theory’s validity. (10.1)
- The continents appeared to fit together, like a puzzle.
- Fossils of the same prehistoric species were found on the continents that were long apart. (10.1)
Seafloor Spreading
the process of new crust forming at the ocean ridges and spreading outwards. (10.1)
Tectonic Plate
Large sections of the crust that move about on Earth’s surface. (10.1)
Subduction
Where one tectonic plate is forced beneath another. (10.1)
Fault Line
A break or crack in Earth’s surface caused by shifting and moving plates.
Magnetic Striping
The patterns of magnetism trapped in rocks on each side of plate boundaries.
Subduction Zone
The region where an oceanic plate sinks down into the asthenosphere at a convergent boundary, usually between continental and oceanic plates (10.1)
Deep-Ocean Trench
A deep area along the ocean floor where oceanic crust sinks towards the mantle. It forms along a subduction zone (10.1)
Asthenosphere
A layer of ‘plastic’ semi-solid rock in the mantle.
Rifting
The process of continents breaking up and allowing in water from the sea. (10.1)
Fault
Cracks in the earth’s crust along which there is movement.
Support for Hess’ theory of seafloor spreading.
- Magnetic Striping
- Age of the seafloor
- Sediment thickness
(10.1)
Outline the two main observations that led Wegener to propose the theory of continental drift.
- The continents fit together, like a jigsaw.
- There were fossils of the same species on continents that weren’t connected.
Hot spot
An area where magma from the earth is hotter and in more quantity than normal. (10.3)
Pangaea
The name of the single landmass that comprised of all the continents. (10.1)
How did Wegener determine Pangaea’s appearance?
Wegener rearranged the continents so that the pieces of the jigsaw fitted and so the fossil distribution was continuous across the land masses. (10.1)
What are the 2 parts of pangaea?
Laurasia and Gondwana(land).
Which continents comprised Laurasia?
North America (Greenland), Europe, and Asia
you don’t have to know this; mark as 5 if you don’t want to
Which continents comprised Gondwanaland?
Antarctica, Australia, South America.
you only have to know Australia.
Describe three types of evidence that now supports the hypothesis of seafloor spreading. (know in detail)
- Rocks at a particular distance from the mid-ocean ridge on one side always had the same magnetic direction as rocks the same distance away
on the other side of the ridge. - The farther the rocks on the seafloor are away from the ridges, the older they are.
- Sedimentary rock layers on the ocean floor become thicker as you move away from the ridges.
(10.1)
Use the theory of plate tectonics to explain why Africa and America are older than the sea floor of the Atlantic Ocean.
New sea floor is constantly being created (seafloor spreading) but the continents were formed billions of years ago and very little land has been formed since then. (10.1)
Volcanoes
A volcano is a place where extremely hot molten rock (magma) from inside the earth erupts at weak spots (hot spots) in the earth’s crust. (10.1)
How does a volcano erupt?
Magma occasionally gets pushed to the surface of the earth and can then be identified as lava. (10.3)
Destructive Boundary
A place where crust (lithosphere) is being destroyed. (10.2)
Constructive Boundary
A place where new crust (lithosphere) is being created. (10.2)
What are the three types of plate boundaries?
Convergent/Collision (destructive), divergent (constructive), transform (10.2)