Unit D Vocabulary

1. Unit D Vocabulary Howard Middle School 6th grade Earth Science

2. Active – A volcano that is currently erupting, showing signs that it is likely to erupt in the near future, or has erupted in recorded history. • Dormant – A volcano that has not erupted for at least 10,000 years, but that scientists think may erupt again.

3. Extinct – A volcano that scientists do not expect to erupt ever again. • Nuclear Waste – Radioactive material that must be disposed because it is not useful. • Magma – Molten rock found beneath the earth’s surface.

4. Core – The innermost area of the earth’s interior. • Crust – The thin outermost “layer” of the earth. • Lava – Molten rock found on top of the earth’s surface.

5. Lithosphere – The rigid upper portion of the earth that is broken into plates. It includes the crust and the uppermost portion of the mantle. • Mantle – The “layer” of the earth between the outer crust and inner core.

6. 11. Cinder Cone – A volcano formed from explosive eruptions that shoot small pieces of magma and ash into the air. 12. Composite Volcano – A volcano that has explosive eruptions as a result of more gassy magma. 13. Cross-section – A slice of an object made by cutting through it in a plane, usually at right angles to an axis.

7. 14. Shield Volcano – A volcano that releases relatively fast-moving, less gassy lava, and tend to have less explosive eruptions. 15. Volcanologist – A scientist who studies volcanoes and volcanic phenomena.

8. 16. Paleontologist – A scientist who uses fossil evidence to study life in prehistoric times. 17. Reptile – Any of various cold-blooded animals, such as snakes, turtles, and crocodiles, that have a backbone. 18. Continent – One of the seven great landmasses of the earth, including Africa, Antarctica, Asia, Australia, Europe, N. America, and S. America

9. 19. Pangaea – A single landmass, or supercontinent, that existed from about 350 million to 200 million years ago and was separated by plate tectonics, forming the current continents. 20. Continental Drift – A theory that the continents were attached together in the past, and have been drifting apart ever since.

10. 21. Plates – Large sections of the earth’s surface. 22. Plate Tectonics – The theory that the rigid outer portion of the earth is broken into large separate sections, called tectonic plates, each moving at a specific speed in a specific direction.

11. Theory – A logically consistent explanation of some aspect of the natural world that is supported by a large body of evidence. • Convection Current – A flow of material (such as magma in the earth’s mantle) caused by a temperature difference.

12. 25. Convergent – A boundary between tectonic plates that are moving toward each other. 26. Divergent – A boundary between tectonic plates that are moving away from each other. Also called a spreading center.

13. 27. Earthquake – The release of energy in the form of waves that occurs when large masses of rock below earth’s surface suddenly shift position. 28. Fault – A crack in a rock mass along which there has been movement caused by the shifting of the earth’s crust.

14. 29. Hot Spot – A place on earth’s surface that is directly above a column of rising magma called a mantle plume. 30. Richter Scale – A scale used to quantitatively rate the magnitude of an earthquake. 31. Risk – The chance that a particular action or event could result in something unfavorable, such as injury or death.

15. 32. Seismogram – The information recorded by a seismograph. 33. Seismograph – An instrument that measures and records the intensity of an earthquake. 34. Subduction – An area where one tectonic plate is being forced downward toward the earth’s interior.

16. 35. Transform – A boundary between tectonic plates that are sliding next to each other.