Quiz 6 (for Week 7 Tuesday 2/25/03) (words from Key Terms section of Chapter 8,
Marshak, 2001, p. 226)
Basement, compositional banding, differential stress, ductile deformation, foliation,
index minerals, metasomatism, migmatite, protolith, schistosity, slaty cleavage
compositional banding- A type of metamorphic foliation defined by alternating bands of
light and dark minerals.
differential stress- The condition in which a material experiences a push or pull in one
direction of a greater magnitude than the push or pull in another direction; in some cases,
differential stress can result in shearing.
Foliation-Layering formed as a consequence of the alignment of mineral grains, or of
compositional banding in a metamorphic rock.
index minerals-Minerals that serve as good indicators of metamorphic grade.
Metasomatism- The process by which a rock’s overall chemical composition changes
during metamorphism because of reactions with hot water that bring in or remove
elements.
Migmatite-A rock formed when gneiss is heated high enough so that it begins to partially
melt, creating layers, or lenses, of new igneous rock that mix with layers of the relict
gneiss.
Protolith-The original rock from which a metamorphic rock formed.
Schistosity-Foliation caused by the preferred orientation of large mica flakes.
slaty cleavage-The foliation typical of slate and reflective of the preferred orientation of
slate’s clay minerals, which allows slate to be split into thin sheets.
flood basalt-Vast sheets of basalt that spread from a volcanic vent over an extensive
surface of land; they may form where a rift develops above a continental hot spot, and
lava is particularly hot and has low viscosity.
Quiz 7 (for Week 8 Tuesday 2/25/03) (words from Key Terms section of Chapters 9
and 10, Marshak, 2001, p. 267 and 307)
Aa, Caldera, Columnar Jointing, Flood Basalt, Ignimbrite, Lahar, Lave Tube, Nuee
Ardente, Pahoehoe, Pillow Lava, Shield Volcano, Stratovolcano, Tephra
aa-A lava flow with a rubbly surface.
Caldera- A large circular depression with steep walls and a fairly flat floor, formed after
an eruption as the center of the volcano collapses into the drained magma chamber
below.
columnar jointing- A type of fracturing that yields roughly hexagonal columns of basalt;
columnar joints form when a dike, sill, or lava flow cools.
Ignimbrite- Rock formed when deposits of pyroclactic flows solidify.
Lahar- A thick slurry formed when volcanic ash and debris mix with water, either in
rivers or from rain or melting snow and ice on the flank of a volcano.
lava tube- The empty space left when a lava tunnel drains; this happens when the surface
of a lava flow solidifies while the inner part of the flow continues to stream downslope.
pillow lava- submarine basaltic lava that forms a glass-encrusted blob (pillow) because
of rapid cooling.
shield volcano- A subaerial volcano with a broad, gentle dome, formed either from lowviscosity basaltic lava or from large pyroclastic sheets.
Stratovolcano- A large, cone-shaped subaerial volclano consisting of alternating layers
of lava and tephra.
Tephra- Unconsolidated accumulations of pyroclastic grains.
Pahoehoe- A lava flow with a surface texture of smooth, glassy, rope-like ridges.
Chapter 10--Brittle Deformation, Ductile Deformation, Epicenter, Fault, Focus,
Love Waves, P-waves, Rayleigh Waves, S-Waves, Seiche
brittle deformation- The cracking and fracturing of a material subjected to stress.
ductile (plastic) deformation- The bending and flowing of a material (without cracking
and breaking) subjected to stress.
Epicenter- The point on the surface of the Earth directly above the focus of an
earthquake.
Fault- A fracture on which one body of rock slides past another.
Focus- The location where a fault slips during an earthquake (hypocenter).
Love Waves
P-waves
Rayleigh Waves
seismic (earthquake) waves- Waves of energy emitted at the focus of an earthquake.
Seiche- Rhythmic movement in a body of water caused by ground motion.