EXAM TWO Flashcards
Chapter 4
Which of the following is NOT a characteristic of an actively erupting volcano?
Totally covered in a fresh blanket of clean, white snow
Chapter 4
Which of the following are ways that viscosity affects gases in magma?
Viscous magma prevents gas from escaping easily.
Chapter 4
Which of these relatively recent volcanic eruptions formed a caldera?
Yellowstone
Chapter 4
How does the silica content affect the behavior of magma?
Higher silica makes the magma more viscous
Chapter 4
Volcanic hazard arising from a collapsing eruption column that runs downhill at high speeds. These are associated with explosive eruptions and a mix of lava lapilli, pumice, ash, and hot gases.
pyroclastic flow
Chapter 4
Which of the following factors indicates a high risk for volcanic mudflows or lahars?
a volcano with a thick covering of snow or ice
Chapter 4
The largest type of volcano is called a _______ volcano and is characterized by broad, low-angle flanks, a small vent or groups of vents at the top, and basaltic magma.
shield volcano
Chapter 5 & 6
What is the difference between weathering and erosion?
Weathering describes how rocks breakdown into smaller pieces, while erosion is the physical removal of those pieces to another location
Chapter 5 & 6
How do chemical and mechanical weathering work together to create sediment?
Mechanical weathering creates surfaces for chemical weathering to take place
Chapter 5 & 6
Clastic sedimentary rocks are defined and named based mainly on their _______________, while chemical sedimentary rocks are defined mainly on their ____________.
grain size, composition
Chapter 5 & 6
What is the most likely cause of a detrital sediment with highly rounded grains?
Shorter time since weathering
Chapter 5 & 6
Which of these indicate changing water conditions, from wet to dry?
Mud cracks
Chapter 5 & 6
Imagine a new and previously unknown sedimentary structure is discovered in a deposit of sedimentary rock. What would be the best approach to try and understand it?
Find a similar structure in a modern environment
Chapter 5 & 6
Water gets into fractures and then freezes, expanding the fracture a little. When the water thaws it seeps a little
farther into the expanded crack. The process is repeated many times, and eventually a piece of rock will be wedged away. This Process is an example for
mechanical weathering
Chapter 5 & 6
What is the sedimentary structure shown in this picture:
cross bedding
Chapter 5 & 6
The principle of original horizontality states that sediments accumulate in essentially _____________. The implication is that tilted sedimentary layers observed today must have been subjected to _______________.
horizontal layers, tectonic forces
Chapter 5 & 6
Which of the sedimentary basins shown here form by stretching and thinning of the continental crust:
a
Chapter 7 & 8
Which of the following matches a sedimentary rock with a possible metamorphic equivalent?
shale-slate
Chapter 7 & 8
Shale is metamorphosed into three rock types: (1) a banded gneissic rock; (2) a rock with small mica crystals with a shiny aspect; (3) a very shiny rock with large mica crystals; and (4) a dull slate with cleavage. Which of the following lists these rocks in order of increasing metamorphic grade?
4, 2, 3, 1
Chapter 7 & 8
A nonfoliated metamorphic rock not created by pressure or differential stress, but by being baked by an igneous intrusion, is a:
hornfels
Chapter 7 & 8
Which location on this diagram would most likely have contact metamorphism around a high-level crustal magma chamber:
d
Chapter 7 & 8
In what environments does high pressure/low temperature metamorphism occur?
in a subduction zone or accretionary prism
Chapter 7 & 8
Missing geologic time caused by erosion is called a (an):
Unconformity
Chapter 7 & 8
If a rock started with 1,000 atoms of a parent but now contains 250 atoms, how many half lives have passed?
2 half lives
Chapter 7 & 8
The Phanerozoic has seen _______ major extinctions.
5
Chapter 7 & 8
This figure shows a disconformity between upper layers (being deposited by the sea) and a lower orange-colored layer. What happened to form this disconformity?
The boundary between the two units indicates that for a time there was either erosion or no deposition.
Which of the following volcanoes is generally the largest?
shield volcano
Which of the following is NOT a characteristic of an actively erupting volcano?
Totally covered in a fresh blanket of clean, white snow
Huge circular depressions from which volcanoes erupt are called:
calderas
Which of the following materials is NOT produced by erupting volcanoes?
sandstone
Which of the following is NOT evidence of recent activity at a volcano?
Thick, well-developed soil
Comparing these two photographs, which eruption has lower viscosity magma?
the fluid cascade of lava
What type of eruption is shown in this photograph?
lava dome
Earthquakes at Mount St. Helens prior to the major eruption in 1980 were caused by:
magma rising in the volcano
Which of the following types of eruptions is among the most deadly of natural disasters?
Caldera-forming
The two main processes by which sediment is produced are:
physical and chemical weathering
Lithifies can be defined as:
loose sediment hardens into sedimentary rock
What happens to the majority of sediment being carried by moving water as it enters a standing body (little or no motion) of water?
The sediment gradually settles to the bottom.
Fluvial refers to:
the processes and sediment of streams and rivers
Downslope marine flows comprised of mixed masses of sand, mud, and water are called:
turbidity currents
Which of the following processes is NOT considered to be chemical weathering?
thermal expansion
Which of the following processes is NOT considered physical weathering?
oxidation
Sedimentary rocks are comprised of material that comes primarily from:
other locations
The effect of transportation on a pebble’s particle size is best summarized by which statement?
Its size decreases.
Compared to non-fractured rocks, the rate of weathering in fractured rocks of the same composition is:
Faster
Which of the following characteristics are NOT used to classify and name clastic sediments?
the climate in which the clasts are produced
Sedimentary clasts are:
loose fragments of rocks and minerals
Clastic sedimentary rocks are classified primarily on the basis of:
sediment size
Which of the following is NOT involved in turning some sediment into sedimentary rock?
metamorphism
What is the main difference between conglomerate and breccia?
the shape of the clasts
Which of the following rocks is composed of the smallest sedimentary clasts?
shale
How does gypsum form?
evaporation of water in a lake or sea
What type of rock forms through solid-state alteration of a previously existing rock, by heating, pressure, and/or fluid chemistry?
metamorphic
What type of tectonic event formed the main structures in the Valley and Ridge Province of the Appalachian Mountains?
a continental collision
Which of the following is most likely to occur at shallow crustal levels?
brittle deformation
When a rock is subjected to tectonic forces and experiences stress that is not the same in all directions, it is under:
differential stress
