Large Scale Geology Vocabulary
1. inner core= a sphere of solid iron and nickel, densest and hottest layer, center of the
Earth
2. outer core= ONLY liquid layer of Earth, iron and nickel
3. mantle= solid (upper) layer then plasticity (flowing solid), thickest layer, density
increases with depth
4. crust= solid layer of Earth, thinnest, coolest, least dense
5. lithosphere= the uppermost part of the mantle (solid) and the crust (solid) together,
100 km, broken up into lithospheric plates
6. asthenosphere=upper mantle, flowing solid, plasticlike
7. scale= each part of the model has a size that is accurate relative to another part (ex.
Action figures, model trains, dolls, solar system replicas) 1 cm= 426 km
8. focus= the point where an earthquake originates, in the lithosphere (100 km), p and s
waves start here
9. epicenter= the point on the Earth's surface that is directly above the focus, area with
the greatest damage, L waves start here
10. Richter Scale= a scale used to quantitatively measure the strength (magnitude) of an
earthquake at the focus
11. seismograph=a machine used to measure the intensity of an earthquake
(seismogram= the lines on the paper)
12. refraction=how waves change speed and direction when they go through various
materials (s,l, or g)
geological time= thousands, millions, even billions of years
Pangaea= the name for the land mass where all continents were joined together, “all lands”
continental drift= continents move, the idea of Pangaea helps explain this
plates= large sections of Earth’s surface that move, made up of the lithosphere (oceanic AND
continental)
13. plate tectonics= the movement of lithospheric plates
14. convergent=colliding, type of plate boundary where two plates are coming closer
together
15. divergent=spreading, type of plate boundary where two plates are moving apart and
new lithosphere is being created (i.e. sea floor spreading or rift valleys)
16. transform= type of plate boundary where two plates slide past one another (across)
17. subduction= the process of one plate moving under another plate, convergent plate
boundary
18. hot spot= in the middle of a plate, a stationary part of the mantle that is so hot that
magma rises through the lithosphere above it resulting in chains of volcanic
mountains/islands (e.g. Hawaii)
19. Deep Ocean Trench- a deep valley along the ocean floor where oceanic lithosphere
subducts into the mantle (CONVERGENT)
20. Island Arc= a string of volcanoes that form islands along a deep ocean trench
(subduction-oceanic vs. oceanic)
21. Mid Ocean Ridge- a string of volcanoes formed at an underwater divergent plate
boundary
22. Seafloor Spreading- the process by which magma adds new oceanic lithosphere to the
ocean floor (divergent boundary)
23. Rift Valley- a deep valley that forms on land when two plates diverge
Stress – a force that acts on rock to change its shape or volume (tension, compression,
shearing)
Fault- a break or crack in Earth’s crust
Normal fault – a type of fault where the hanging wall slides down, caused by tension (divergent
boundary)
Reverse fault – a type of fault where the hanging wall slides up; caused by compression
(convergent)
Strike-slip fault – a type of fault in which rocks move side to side, caused by shearing
(transform)
Syncline – a downward fold in rock formed by compression
Anticline – an upward fold in rock formed by compression
active volcano= currently erupting or are showing signs that they will soon erupt
dormant volcano= ones that have not erupted for at least 10,000 years but may erupt again,
sleeping giants
extinct volcano= ones that are not expected to erupt again
magma= hot liquid-like rock that is found BELOW Earth’s surface
lava= magma that has erupted onto Earth’s surface (ABOVE)
granite= igneous rock found in continental crust (less dense than basalt)
basalt= igneous rock found in oceanic crust (denser than granite)
convection current= the movement in Earth’s mantle in which fluid is circulated due to
differences in temperature