Unit D Vocabulary
Howard Middle School
6th grade
Earth Science
1. 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.
2. 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.
4. Nuclear Waste – Radioactive
material that must be disposed
because it is not useful.
5. Magma – Molten rock found
beneath the earth’s surface.
6. Core – The innermost area of the
earth’s interior.
7. Crust – The thin outermost “layer”
of the earth.
8. Lava – Molten rock found on top of
the earth’s surface.
9. Lithosphere – The rigid upper
portion of the earth that is broken
into plates. It includes the crust
and the uppermost portion of the
mantle.
10. Mantle – The “layer” of the earth
between the outer crust and inner
core.
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.
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.
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
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.
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.
23.Theory – A logically consistent
explanation of some aspect of the
natural world that is supported by a
large body of evidence.
24.Convection Current – A flow of
material (such as magma in the
earth’s mantle) caused by a
temperature difference.
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.
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.
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.
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.
35. Transform – A boundary between
tectonic plates that are sliding next to
each other.