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Q:
In a given area where you have little knowledge of the local geology (rocks types, fossils, etc.), what type of unconformity would be the most difficult to recognize in an exposed sequence of rocks? Why?
Q:
Compare and contrast relative age dating with radiometric age dating. What is a limitation (if any) of each?
Q:
All of geologic time prior to the beginning of the Paleozoic era is commonly referred to as the ________ era.
Q:
We now live in the ________ era.
Q:
What is the name of a Phanerozoic era that means ancient life?
Q:
Isotopes of what element are the stable, end products of both uranium decay series?
Q:
For a radioactive isotope like Uranium-235, what does the 235 indicate?
Q:
What is the inert gas, daughter product of the radioactive isotope, K-40?
Q:
What are the mass and charge of an alpha particle?
Q:
What process involves identifying and matching rocks of similar ages in different areas?
Q:
The remains or traces of prehistoric life are called ________.
Q:
An unconformity in which the strata on either side are essentially parallel is termed a(n) ________.
Q:
In an undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below. The preceding is a statement of the law of ________.
Q:
In the interior of continents the earth's crust is typically about 40 km thick and the elevation is near sea level. In the Himalayas the crust is more than 60km thick. Isostasy says crust thicker than this average should produce elevated terrain (mountains), so why isn't the elevation of the Himalayas 20km?
Q:
The Appalachians and Himalaya are a classic collisional mountain belts yet the elevation of the Appalachians mountains is a tiny fraction of the lofty Himalaya. Why are these two collisional mountain belts so different?
Q:
The Laramide Rockies formed between about 85-50 million years ago. A popular theory is this event was caused by "flat slab subduction" of over-thickened oceanic crust. From your understanding of mountain building processes in this part of the course, evaluate the following question(s).
If these mountains formed 50 million years ago, why are they still high?
Q:
The Laramide Rockies formed between about 85-50 million years ago. A popular theory is this event was caused by "flat slab subduction" of over-thickened oceanic crust. From your understanding of mountain building processes in this part of the course, evaluate the following question(s).
Was this mountain building process an Andean type mountain building event, a collisional event, or both; and what might have been subducted to produce the over-thickened oceanic crust that drove the orogeny?
Q:
A region is characterized by numerous anticlines and synclines. There are also several faults present that appear to have formed at the same time as the folding. Without looking at any details, what type of faults would be most likely? Why?
Q:
Evaluate the following statement, addressing what parts, if any, are right and which are wrong:
Jointing in rocks does not affect the flow of groundwater at depths greater than 10-20m because all fractures close below that depth. Jointing is important, however, to engineers interested in stability of slopes and locating structures because joints can slide or open under gravitational forces on slopes.
Q:
In the figure below, which occurred first, the folding or the faulting? Briefly explain your answer.
Q:
Briefly describe how time, temperature, mineralogy, and confining pressure affect the way a rock will deform when the differential stresses on the rock exceed the strength of the rock.
Q:
Refer to the figure below, captured from Google Earth, for the following questions. At location D you would expect to find ________ faults.
Q:
Refer to the figure below, captured from Google Earth, for the following questions. The line of volcanos at C is called a ________.
Q:
Refer to the figure below, captured from Google Earth, for the following questions. At location B you might expect to find a ________ basin
Q:
Refer to the figure below, captured from Google Earth, for the following questions. Location A would be an area where you would expect ________ faulting
Q:
Oceanic plateaus and seamounts are both bathymetric highs on the seafloor. When they encounter a subduction zone oceanic plateaus are generally accreted to become a(n) ________ whereas seamounts typically are ________.
Q:
Recall that the Hawaiian Islands are a large volcanic chain on the Pacific produced by the Pacific plate moving over a hot spot. When the Hawaiian islands reach a trench and they are accreted to a continental margin they would produce a(n) ________ comprised primarily of the rock type called ________.
Q:
Any accreted crustal fragment that has a geologic history distinct from that of the adjoining fragments is termed a(n) ________.
Q:
Based on your knowledge of isostasy, would you expect thicker or thinner crust beneath the Caribbean Islands (e.g., near D) than the continental region of Venezuela to the south?
Q:
The figure above shows a popular area for North American tourists in winter, the Caribbean region. Match the term to the letter on the Figure.
Trench
Q:
The figure above shows a popular area for North American tourists in winter, the Caribbean region. Match the term to the letter on the Figure.
Island arc
Q:
The figure above shows a popular area for North American tourists in winter, the Caribbean region. Match the term to the letter on the Figure.
Accretionary Wedge
Q:
The figure above shows a popular area for North American tourists in winter, the Caribbean region. Match the term to the letter on the Figure.
Forearc Basin
Q:
The figure above is an oblique Google earth image from southwestern North America looking approximately north. The view is approximately 50km across. The area is a classic area of normal faulting.
The topographic highlands, or ranges, in this area labeled A are also called ________ blocks.
Q:
The figure above is an oblique Google earth image from southwestern North America looking approximately north. The view is approximately 50km across. The area is a classic area of normal faulting.
Topographic basins like the areas labeled B in this figure are called ________.
Q:
On the blanks provided below, fill in the name of the specific type of geologic features that have been labeled.
Q:
Carefully study each illustration below to determine the type(s) of geologic structure(s) it contains. Match each one to the correct answers listed. reverse fault
monocline
normal fault ________
Q:
Carefully study each illustration below to determine the type(s) of geologic structure(s) it contains. Match each one to the correct answers listed. reverse fault
monocline
normal fault ________
Q:
Carefully study each illustration below to determine the type(s) of geologic structure(s) it contains. Match each one to the correct answers listed. reverse fault
monocline
normal fault ________
Q:
Fractures in rock with no conspicuous offset are called ________.
Q:
A(n) ________ fault forms when the hanging wall moves down relative to the footwall .
Q:
What type of structure is shown below?
Q:
Exhumed basins contain ________ rocks in the center of the structure and domes contain ________ rocks in the center.
Q:
When the hinge line of a fold is not horizontal the fold is said to ________.
Q:
Which letter in the figure corresponds to a "fault"?
Q:
Which letter in the figure above corresponds to a "syncline"?
Q:
Changes in the shape of a rock body in response to a differential stress is called ________.
Q:
Terrane accretion generally occurs along a divergent boundary between a continental plate and an oceanic plate.
Q:
Subduction produces mountains because subduction zones are the upwelling zones of mantle convection, which lifts the earth's surface to form mountains.
Q:
Subduction only occurs when oceanic rocks are forced beneath a continent.
Q:
Orogenesis refers to the formation of mineral deposits.
Q:
The hinge of a fold must lie within the axial plane of the fold.
Q:
When the differential stress exceeds the strength of the material, the material will begin to undergo elastic strain.
Q:
Refer to the figure below, captured from Google Earth, for the following questions. This mountain belt would be called ________.
A) a collisional mountain belt
B) a terrane accretion mountain belt
C) an Andrean mountain belt
D) fault block mountains
Q:
Ocean spreading centers are highlands on the ocean floor, sometimes referred to as submarine mountains. Oceanic crust worldwide is about the same thickness so isostasy would suggest the ocean floor should be as flat as Kansas. Which of the following statements best describes the origin of these submarine mountains?
A) The ridges are sites of young volcanos that produce high topography on the sea floor, like Hawaii.
B) The ridges represent upwelling zones from the core which produces a bulge at the earth's surface.
C) Compression at the ridges produce local uplift along the ridge axis.
D) The mantle beneath the ridges remains hot for millions of years producing an elevated region along the ridge axis because hot rocks are lower density than cold rocks.
Q:
In the interior of continents the earth's crust is typically about 40km thick and the elevation is near sea level. Most earth materials expand when heated, lowering their density. During rifting continental margins are heated but cool as sea floor spreading moves offshore from the continent. Thus, basic isostasy suggests that after rifting, a continental margin will ________.
A) uplift
B) subside
C) remain near sea level
D) rise slowly as erosion removes uplifted rocks
Q:
In the interior of continents the earth's crust is typically about 40km thick and the elevation is near sea level. In an area where the crust is 20km thick, isostasy would suggest the elevation in this area would be ________ unless the density changes from one area to the other.
A) below sea level
B) near sea level
C) slightly above sea level
D) high mountains
Q:
A thrust fault increases the thickness of the crust as it moves toward a continental interior in a mountain belt; yet the crust beyond the mountain front stays the same thickness. Isostasy would suggest that the area at the mountain front, where the thrust emerges, should ________ over time.
A) uplift
B) stay the same
C) subside
D) near sea level
Q:
Most geologists think the elevation of mountains above sea level is limited by earth's gravity because ________.
A) rocks can never reach escape velocity
B) rock cliffs are subject to gravity failure and can only be about 1km high
C) the earth's mantle is too weak to support the load of large mountains
D) thickening of the crust in mountain belts produces a weak deep crust the spreads by gravity collapse, limiting the elevation
Q:
The Tibetan plateau is high above sea level because ________.
A) there are many active faults across Tibet that produce internal crustal thickening and uplift
B) the extrusion of East Asia has produced structures that thicken the crust under Tibet, producing regional uplift
C) a giant fault beneath Tibet raises it up relative to adjacent areas
D) crustal thickening over millions of years has produced a thick crust that stands high due to Isostasy
Q:
The Rocky Mountains of western North America were produced in an orogeny called the ________.
A) Absaroka orogeny
B) Laurentide orogeny
C) Uinta orogeny
D) Laramide orogeny
Q:
Mountain building in the western margin of North America records a history of both ________.
A) continental collision and terrane accretion
B) Andean type subduction and terrane accretion
C) Andean type subduction and continental collision
D) none of the above
Q:
The Appalachian Mountains may have once been as lofty as the Himalayan-Tibetan Mountain belt is today. Why are they not this high now?
A) They developed a dense crustal root following collision, and isostasy forced them to sink to their present elevation.
B) They formed long ago, and erosion has beveled them to their present low elevation.
C) The mountains cooled following the collision, which increased the density of the of the rocks by cooling, and isostasy forced the mountains to sink.
D) Opening of the North Atlantic Ocean converted lithosphere to asthenosphere beneath eastern North America, forcing eastern North America to sink to low elevations.
Q:
Folded limestones that are exposed high elevations in the Himalayas were originally deposited as sediments in a ________.
A) marine basin between India and Eurasia.
B) Cenozoic fault basin between Africa and Arabia.
C) deep ocean trench along the southern margin of India.
D) late Paleozoic syncline north of the Tibetan Plateau.
Q:
The ________ is (are) characterized by terrane accretion that has been active throughout most of Mesozoic and Cenozoic time.
A) western margin of Africa
B) southern margins of India and Australia
C) western margin of North America
D) western margin of the Mid-Atlantic Ridge
Q:
The Appalachians were formed by three phases of ________ orogeny.
A) collisional
B) Andean
C) rifting
D) transform
Q:
A widely cited theory associates active faults and earthquakes in China and southeast Asia to the India-Eurasia collision. This theory suggests ________.
A) East Asia is moving toward the Himalaya, causing faulting and earthquakes
B) subduction beneath East Asia is pushing East Asia toward the Himalaya, forming young mountains between the Himalaya and Pacific subduction zones
C) India is moving west relative to Eurasia, pulling central Asia away from East Asia
D) India is plowing into the "soft underbelly" of Asia, pushing East Asia eastward
Q:
The boundary between two terranes or two continents that have collided is called a ________.
A) suture
B) join
C) weld
D) stitch
Q:
Island arc systems now on the Tibet plateau record subduction prior to the collision of India with Eurasia. Geologists would map these pre-collisional arc rocks as ________.
A) hot spot tracks
B) terranes
C) rift zones
D) pre-collisional transform zones
Q:
The Himalayas and Tibet are the archetypical example of a(n) ________ mountain belt.
A) Andean
B) continental rift
C) transform
D) collisional
Q:
The Peninsular terrane is now part of the crust of North America in southern Alaska. The dominant rock type in this terrane is intrusive igneous rock that ranges in composition from gabbro to granite and volcanic rock with a similar compositional range. Geologic evidence indicates the Peninsular terrane collided with North America during late Mesozoic time. Which of the following would be the most reasonable interpretation for the origins of the Peninsular terrane?
A) a Mesozoic island arc
B) a Mesozoic oceanic plateau
C) a Mesozoic accretionary wedge
D) a Cenozoic forearc basin
E) a Paleozoic accretionary wedge
Q:
The Sierra Nevada Mountains of California, and the Teton Mountains of Wyoming, ranges are examples of ________.
A) fault blocks uplifted by late Tertiary to Quaternary normal faulting
B) folding, compression, and thickening of Paleozoic strata in Jurassic time
C) isostatic uplift of crust over thickened in early Paleozoic time
D) uplifted blocks bounded by Quaternary reverse faults
Q:
In what part of a subduction margin might you find rocks deposited on the abyssal plain, far from land?
A) Accretionary Wedge
B) Volcanic Arc
C) Forearc Basin
D) Cratonic Basin
Q:
What type of basin would be most likely to contain large amounts of sediments derived from a volcanic source?
A) a continental interior basin
B) a passive continental margin
C) a forearc basin
D) a strike-slip basin
Q:
Studies of the chemistry of rocks from arc volcanos indicate the main source of the magma is ________.
A) melting of subducted oceanic crust
B) melting of the subducted mantle lithosphere
C) melting of the asthenosphere above the subducting oceanic plate by frictional heating on the subduction interface
D) melting of the asthenosphere above the subducting oceanic plate by fluids acting as a flux to enhance melting
Q:
Granitic batholiths typically form over time intervals of ________.
A) tens of thousands of years
B) hundreds of thousands of years
C) millions of years
D) billions of years
Q:
You are walking on the beach along the south-coast of Alaska. You see rocks cut by numerous faults that consist of basalt with evidence of eruption in the ocean, deep-water chert, mudstone, and sandstones with abundant volcanic material. What tectonic setting would you assign to these rocks?
A) passive continental margin sequence
B) forearc basin
C) continental interior basin
D) accretionary wedge
Q:
A good example of a present-day, passive continental margin is the ________.
A) north flank of the East Pacific Rise
B) west coast of South America
C) east coast of the Japanese Islands
D) east coast of North America
Q:
A(n) ________ is a thick accumulation of sediments and small tectonic blocks formed of material scraped off subducting oceanic lithosphere at a convergent margin.
A) mass movement complex
B) continental shelf, terrain complex
C) accretionary-wedge complex
D) subterranean-accumulation complex
Q:
The west coast of California is underlain by rocks that represent ________.
A) an ancient volcanic arc
B) an ancient Forearc Basin and accretionary wedge
C) a collisional orogenic belt
D) an oceanic plateau