Plate Boundary

11. Plate Boundary Plate boundaries are found where tectonic plates meet. There are three kinds: Plates move together at convergent boundaries, plates move apart at divergent boundaries, and plates move side-by-side at transform boundaries.

12. Plate Tectonics The theory that tectonic plates move slowly over time to cause geologic events such as earthquakes, volcanoes, mountain building, and sea floor spreading. Scientists estimate that the plates move between 1-10 cm per year and is caused by heat convection within the earth.

13. Stress Force applied to tectonic plates that can cause changes in the geologic landscape.

14. Compression Tectonic stress that results from two tectonic plates pushing against each other. This happens at convergent boundaries and can result in the formation of mountains or ocean trenches.

15. Tension Tectonic stress that results from two tectonic plates pulling apart. This happens at divergent boundaries and can result in sea-floor spreading.

16. Shearing Tectonic stress that results from two parallel tectonic plates sliding past each other. This happens at transform boundaries and can cause fracturing of rock at the fault line.

17. Sea-floor Spreading A process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge

18. Pangaea The supercontinent that formed 300 million years ago. Pangaea began to break apart 200 million years ago and the continents were separated into their current positions.

19. Rift Valley A rift valley is a lowland between two highlands or mountain ranges created at a divergent fault. When the plate splits apart the center block will drop down relative to the sides.

20. Plateau A high plain elevated relative to the rest of the landscape. Plateaus can be created by an upwelling of magma in the mantle that causes the crust to swell above.