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GEOL EXAM2
CWI GEOL EXAM 2
Question | Answer |
---|---|
Lava flows are typically finer grained than intrusive Igneous rocks. Why? | The extrusive magma cools quickly so the mineral grains do not have time to grow |
Nonclastic textures are common in which of the following sedimentary rocks? | limestones |
Mount St. Helens is ____. | an explosive stratovolcano |
Which one of the following statements concerning soil erosion is not true? | Sheet erosion, rills, and gullies develop mainly during prolonged droughts. |
A glassy texture is developed when a magma cools | Very quickly, over the course of hours to days |
Which of the following is not a mode of transport for clastic materials? | dissolved ions in solution |
Which of the following is not a major factor in magma viscocity? | Temperature |
In which area would weathering by frost wedging probably be most effective? | in moist, temperature climates |
The sizes, shapes, and arrangements of mineral grains in an igneous rock is known as ____. | texture |
Coal beds originate in ___. | freshwater coastal swamps and bogs |
Kilauea and Mauna loa are ____. | basaltic shield volcanoes |
Which term best describes an accumulation of angular rock fragments at the base of a steep, bedrock slope or cliff? | talus slope |
If the material accumulated at the base of a steep bedrock cliff face were to become lithified, what rock type would most likely result? | Breccia |
A ____ is an open cavity in a volcanic rock that was filled by a gas bubble when the lava was still mainly liquid. | vesicle |
When a geologists observes vesicles in basaltic lava flows they typically find them: | concentrated near the top of the flow |
Which of the following sedimentary features can each be used to determine paleocurrent directions? | ripple marks and cross stratification |
Which kind of eruptive activity is most likely to be highly explosive? | Eruptions of big, continental margin, composite cones or stratovolcanoes. |
What mineral particles are the dominant coloring agents in reddish, brownish, and yellowish soils? | dust-sized grains of iron oxides |
In a porphyritic volcanic rock, which mineral grains are the last to crystallize? | matrix or groundmass |
Oolitic limestone is most likely to form in what type of depositional environment? | shallow, clear, marine waters with vigorous wave activity |
Visible quartz and potassium feldspar grains are the main constituents in a ___. | granite |
Which term describes a soil formed by weathering of the underlying bedrock? | transported |
Which of the following minerals crystallized early in Bowen's reaction series? | olivine |
Which of the following is not a type of limestone? | arkose |
The Columbia Plateau in Washington, Oregon, and parts of Idaho is ____. | a flood basalt plateau |
Which one of the following statements concerning mechanical weathering is not true? | involves a major change in the mineral composition of the weathered material |
____ is characterized by very coarse mineral grains? | Pegmatite |
Which of the following sedimentary features would typically be found in shales but not in sandstones? | mud cracks |
Which type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble? | aa |
Which of the following best describes sets of fractures in relatively fresh bedrock, such as granite, that are roughly parallel to the land surface? | sheeting fractures |
What do pumice and obsidian have in common? | glassy texture |
Detrital grains of which mineral(s) are extremely rare in detrital sediments? Why? | calcite; it is soft and relatively soluble |
Why would a plume of solid silicate rock rising slowly from deep in the mantle begin melting as it neared the base of the lithosphere? | Temperatures remain high as lowered pressures decrease melting temperatures. |
Which type of sediment undergoes the most compaction as it lithifies to sedimentary rocks? | marine mud |
Which of the following is associated with deep mantle hot spots? | the volcanoes of Hawaii and the recent activity in Yellowstone National Park |
In the Rocky Mountain region of the United States, north-facing slopes (downhill direction is toward the north) are typically more moist and heavily forested than south-facing slopes. Why? | North-facing slopes receive about the same amount of precipitation as south-facing slopes; less moisture evaporates from north-facing slopes. |
Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage). Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)? | 5%; 75% |
In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion? | apples; land between the trees is planted in grass and not cultivated |
A cherty limestone would contain which major constituents? | silca; calcite |