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
