Geology Lab vocab pt. 2

  1. Schistosity
    Geological foliation (metamorphic arrangement in layers) with medium to large grained flakes in a preferred sheetlike orientation
  2. Gneissic banding
    Banding exhibited by certain igneous rocks of heterogeneous composition
  3. Porphyroblasts
    a larger recrystallized grain occurring in a finer groundmass in a metamorphic rock.
  4. Parent rock
    the original rock from which something else was formed
  5. Continental drift
    the gradual movement of the continents across the earth's surface through geological time.
  6. Sea-floor spreading
    the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side.
  7. Convergent plate boundaries
    an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide.
  8. Divergent plate boundaries
    a linear feature that exists between two tectonic plates that are moving away from each other.
  9. Transform plate boundaries
    a type of fault whose relative motion is predominantly horizontal
  10. Fault
    a crack in the Earth's crust
  11. Normal fault
    where two blocks of rock are pulled apart, as by tension
  12. Reverse fault
    a geological fault in which the hanging wall appears to have been pushed up along the footwall
  13. Strike-slip/transform fault
    a fault in which rock strata are displaced mainly in a horizontal direction, parallel to the line of the fault.
  14. Footwall
    the block of rock that lies on the underside of an inclined fault or of a mineral deposit.
  15. Hanging wall
    the block of rock that lies above an inclined fault or an ore body.
  16. Lithosphere
    the rigid outer part of the earth, consisting of the crust and upper mantle.
  17. Asthenosphere
    the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
  18. Decompression melting
    the upward movement of the earth's mantle to an area of lower pressure
  19. Geologic record
    the history of Earth as recorded in the rocks that make up its crust
  20. Relative age dating
    the science of determining the relative order of past events, without necessarily determining their absolute age
  21. Absolute age dating
    the process of determining an age on a specified time scale in archaeology and geology
  22. Disconformity
    a break in a sedimentary sequence that does not involve a difference of inclination between the strata on each side of the break.
  23. Angular unconformity
    an unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers
  24. Nonconformity
    the sedimentary rock lies above and was deposited on the pre-existing and eroded metamorphic or igneous rock.
Card Set
Geology Lab vocab pt. 2
Geology Lab vocab pt. 2