MOCK EXAM Flashcards
Which of the following statements best explains the significance of the Kármán Line in defining the boundary between Earth’s atmosphere and outer space?
A. The Kármán Line is located at an altitude where atmospheric pressure drops to zero, marking the start of outer space.
B. The Kármán Line is the altitude at which the gravitational pull of Earth becomes negligible, indicating the beginning of outer space.
C. The Kármán Line is the altitude where the atmosphere becomes too thin for aerodynamic flight, marking the boundary between the atmosphere and outer space.
D. The Kármán Line is the point where the temperature of the atmosphere drops to absolute zero, signifying the start of outer space.
The Kármán Line is the altitude where the atmosphere becomes too thin for aerodynamic flight, marking the boundary between the atmosphere and outer space.
Which of the following seismic discontinuities marks the boundary between the Earth’s mantle and the outer core, characterized by a sudden change in seismic wave velocities?
A. D” Layer
B. Gutenberg Discontinuity
C. Lehmann Discontinuity
D. ULVZ
Gutenberg Discontinuity
A geologist is studying a region where two lithospheric plates are converging. The area is characterized by intense seismic activity, volcanic arcs, and the presence of a deep oceanic trench. Based on these observations, which type of plate boundary is most likely present, and what specific geological process is occurring?
A. Continental-continental convergence; formation of a mountain range due to crustal thickening.
B. Oceanic-continental convergence; subduction of the oceanic plate beneath the continental plate, leading to volcanic arc formation.
C. Oceanic-oceanic convergence; subduction of one oceanic plate beneath another, resulting in the formation of an island arc and trench.
D. Transform boundary; lateral sliding of plates past each other, causing earthquakes but no significant volcanic activity.
Oceanic-oceanic convergence; subduction of one oceanic plate beneath another, resulting in the formation of an island arc and trench.
Which of the following best describes the primary mechanism that initiated the formation and movement of tectonic plates on Earth?
A. The differentiation of Earth’s core, leading to the formation of rigid lithospheric plates that float on the semi-fluid asthenosphere.
B. The cooling and solidification of Earth’s early magma ocean, driven by mantle convection currents and slab pull forces.
C. The gravitational collapse of early continental crust, resulting in the fragmentation and lateral movement of lithospheric plates.
D. The accumulation of sedimentary layers on the ocean floor, causing the lithosphere to break into plates due to differential loading.
Answer: The cooling and solidification of Earth’s early magma ocean, driven by mantle convection currents and slab pull forces.
Differentiation of Earth’s core: While important, this process primarily describes the formation of Earth’s layers rather than the initiation of plate movement.
Gravitational collapse of early continental crust: This is not a recognized mechanism for plate tectonics; rather, it oversimplifies complex geological processes.
Accumulation of sedimentary layers: This does not initiate tectonic movements; it’s more a consequence of geological processes rather than a driving mechanism.
A geologist is assessing the impact of extensive groundwater extraction from a coastal aquifer. They observe a decline in the water table, increased salinity in nearby wells, and land surface sinking. Which combination of processes best explains these observations?
A. Saltwater intrusion and cone of depression
B. Cone of depression and upconing
C. Upconing and ground subsidence
D. Saltwater intrusion and ground subsidence
Answer: Saltwater intrusion and ground subsidence
Saltwater intrusion and cone of depression: While a cone of depression occurs due to over-pumping, it does not fully encompass the subsidence aspect.
Cone of depression and upconing: Upconing refers to the upward movement of saltwater into freshwater zones, which isn’t directly indicated by the observations.
Upconing and ground subsidence: Upconing is not as relevant as saltwater intrusion in explaining increased salinity in wells; thus, this option does not adequately address the primary processes at play.
Which of the following provides the most reliable evidence for the general direction of tectonic plate movements.
A. The alignment of volcanic island chains
B. The distribution of earthquake epicenters
C. The orientation of magnetic stripes on the ocean floor
D. The pattern of sediment deposition in ocean basins
The orientation of magnetic stripes on the ocean floor
What is the average rate of movement and general direction of the Pacific Plate?
7-11 cm/year, moving northwest
Determine which process best explains the formation of the Ninety East Ridge (NER). The NER is a mid-ocean ridge on the Indian Ocean floor named for its near-parallel strike along the 90th meridian at the center of the Eastern Hemisphere. It is approximately 5,000 km in length and can be traced topographically from the Bay of Bengal southward towards the Southeast Indian Ridge (SEIR), though the feature continues to the north where it is hidden beneath the sediments of the Bengal Fan.
A. Subduction of the Indian Plate beneath the Eurasian Plate
B. Divergence of the Indian Plate and the Australian Plate
C. Movement of the Indian Plate over a stationary hotspot
D. Transform faulting between the Indian Plate and the Antarctic Plate
Movement of the Indian Plate over a stationary hotspot
It is a type of mountain building characterized by subduction beneath a continent rather than oceanic lithosphere. Subduction along these active continental margins is associated with long-lasting magmatic activity that builds continental volcanic arcs. The result is crustal thickening, with the crust reaching thicknesses of more than 70 kilometers (45 miles).
A. Island Arc-Type
B. Cordilleran-Type
C. Andean-Type
D. Alpine-Type
Answer: Andean-Type because this type of mountain building specifically occurs when an oceanic plate subducts beneath a continental plate, leading to the formation of continental volcanic arcs.
Island Arc-Type: Involves oceanic-oceanic subduction, forming volcanic islands.
Cordilleran-Type: Generally refers to mountain ranges formed by various processes, including continental collisions, but is less specific than Andean-Type.
Alpine-Type: Typically involves continental collisions rather than subduction beneath a continent.
Interpret the following scenarios to determine which type of deformation is most likely to occur in the vicinity of an active subduction zone experiencing significant volcanic activity.
A. Horizontal extension and normal faulting
B. Vertical uplift and reverse faulting
C. Horizontal compression and strike-slip faulting
D. Vertical subsidence and thrust faulting
Answer: Vertical uplift and reverse faulting
Horizontal extension and normal faulting: This typically occurs in divergent boundaries, not at subduction zones.
Horizontal compression and strike-slip faulting: While horizontal compression occurs, strike-slip faulting is more characteristic of transform boundaries.
Vertical subsidence and thrust faulting: Thrust faulting does occur at subduction zones, but vertical subsidence is not a primary feature; instead, uplift is more common in these settings.
P-waves cause _____ compression and expansion, while S-waves cause _____ shearing.
Vertical compression; horizontal shearing
Very high/Critical flood susceptibility areas are likely to experience flood heights of ____ and/or flood duration of more than ____
more than 2.0 meters; 3 days
Moderate flood susceptibility areas are likely to experience flood heights of ____ and/or flood duration of ____
0.5 to 1.0 meters; 1 to 3 days
These leucocratic intrusive orthogneiss suite are common in Archean terranes. They have typical granitic composition but only a small portion of potassium feldspar.
TTG (Tonalite-Trondhjemite (Plagiogranite)-Granodiorite)
is an extrusive rock high in both magnesium and silica, thought to be usually formed in fore-arc environments, typically during the early stages of subduction.
A. Boninites
B. Trondhjemites
C. MORBs
D. Tonalites
Answer: Boninites
TTG (Tonalite-Trondhjemite (Plagiogranite)-Granodiorite)- These leucocratic intrusive orthogneiss suite are common in Archean terranes. They have typical granitic composition but only a small portion of potassium feldspar.
MORBs- At ocean spreading centers, partial melting of lherzolite generates voluminous and geochemically distinct containing minerals such as plagioclase, augite, hypersthene, pigeonite, diopside, and olivine.
During a field study, a geologist discovers a volcanic rock with a porphyritic texture, containing phenocrysts of plagioclase and pyroxene in a fine-grained matrix. The geologist concludes that the rock likely formed from a magma that experienced two stages of cooling. Which of the following best describes the likely environment of formation?
A. Continental hotspot
B. Oceanic hotspot
C. Subduction zone
D. MOR
Answer: Oceanic hotspot because the porphyritic texture and presence of plagioclase and pyroxene suggest a magma that cooled slowly at depth before erupting, typical of hotspot volcanism.
A. Continental hotspot: Generally produces rhyolitic or andesitic rocks, not typically characterized by the described mineralogy.
C. Subduction zone: While it can produce porphyritic textures, it usually involves more complex interactions and different mineral assemblages due to the melting of subducted materials.
D. MOR (Mid-Ocean Ridge): Primarily produces basaltic rocks with rapid cooling, lacking the two-stage cooling process indicated by the porphyritic texture.
It is a sedimentary unit with consistent characteristics (lithology, grain size, texture, structures, etc.) that formed under specific depositional conditions.
a. Strata/Stratum
b. Formation
c. Sedimentary Facies
d. Lithofacies
Answer: Sedimentary Facies
a. Strata/Stratum: Refers to layers of sedimentary rock that are distinct from one another, but does not specifically denote consistent characteristics formed under specific conditions.
b. Formation: A geological unit that is typically larger than a facies and encompasses multiple facies. It may consist of various sedimentary facies but does not imply uniformity in characteristics.
d. Lithofacies: Similar to sedimentary facies, but it emphasizes the lithological characteristics. While it may be applicable, “sedimentary facies” is more commonly used in the context of depositional environments.
A geologist is studying a metamorphic rock sample and identifies the presence of garnet, staurolite, and kyanite. The geologist infers that the rock underwent regional metamorphism at high pressure and moderate temperature. Which of the following protoliths is most likely to have produced this metamorphic assemblage?
A. Basalt
B. Shale
C. Limestone
D. Sandstone
Answer: Shale. This sedimentary rock is rich in clay minerals and is the typical parent rock for the formation of garnet, staurolite, and kyanite during regional metamorphism under high pressure and moderate temperature conditions. These minerals are common in pelitic (clay-rich) metamorphic rocks formed from shale.
Basalt: This igneous rock typically undergoes different metamorphic processes, leading to the formation of minerals such as amphibole and pyroxene.
Limestone: This sedimentary rock primarily transforms into marble under metamorphism, producing calcite and dolomite.
Sandstone: This sedimentary rock primarily transforms into quartzite
It is the process of transforming detrital grains into sedimentary rocks.
A. Diagenesis
B. Lithification
C. Compaction
D. Cementation
Answer: Lithification
Diagenesis - Broader, also includes Lithification
Cementation - Only a part of Lithification
A geologist is tasked with assessing the erosion rates of a riverbank composed of various sedimentary layers. The geologist collects samples from different depths and analyzes the grain size distribution, mineral composition, and cohesion properties. Based on the following data, which layer is most likely to experience the highest rate of erosion?
A. Layer 1: Fine-grained siltstone, high clay content, moderate cohesion
B. Layer 2: Coarse-grained sandstone, low clay content, low cohesion
C. Layer 3: Medium-grained shale, high clay content, high cohesion
D. Layer 4: Fine-grained limestone, low clay content, moderate cohesion
Answer: Layer 2 (Coarse-grained sandstone): This layer has low cohesion and consists of larger grains that are more easily dislodged by water flow, making it highly susceptible to erosion.
Layer 1 (Fine-grained siltstone): While it has moderate cohesion, the fine grain size typically leads to lower erosion rates compared to coarser materials.
Layer 3 (Medium-grained shale): High clay content and high cohesion provide better resistance to erosion.
Layer 4 (Fine-grained limestone): Moderate cohesion and fine grain size also contribute to lower erosion rates.
A hydrologist is tasked with estimating the average annual precipitation over a watershed using the isohyetal method. The watershed is divided into several zones by isohyetal lines, each representing different precipitation amounts. The areas and corresponding precipitation values for each zone are as follows:
Zone 1: 12 km², 750 mm
Zone 2: 18 km², 850 mm
Zone 3: 30 km², 950 mm
Zone 4: 25 km², 1200 mm
What is the correct average annual precipitation for the watershed?
1. Calculate Total Precipitation for Each Zone:
Zone 1: 12 km2 × 750 mm = 9000 km 2⋅mm
Zone 2: 18 km2 × 850 mm = 15300 km2⋅mm
Zone 3: 30 km2 × 950 mm = 28500 km2⋅mm
Zone 4: 25 km2 × 1200 mm = 30000 km2⋅mm
2. Sum Total Precipitation:
Total Precipitation = 9000+15300+28500+30000=82800 km2⋅mm
3. Sum Total Area:
Total Area = 12+18+30+25=85 km2
4. Calculate Average Annual Precipitation:
Average Annual Precipitation = Total Precipitation/Total Area = 82800/ 85
Average Annual Precipitation = 974.12 mm
Calculate the total porosity given the following: total volume of the earth material= 100 cm3; volume of water remaining in the material after gravity drainage= 10 cm3; volume of water that was drained from the earth material= 30 cm3
- Total Porosity(ϕ) = Pore Volume (Vp) / Total Volume (Vt)
- Pore Volume (Vp) = Volume of water remaining in the material after gravity drainage (Vrem) + Volume of water that was drained from the earth material (Vd)
ϕ = (Vrem + Vd) / Vt
ϕ = (10 + 30)/100
ϕ = 0.4
These dunes develop through the saltation of sand grains up their gentle sloping windward slope, and settle by the angle of repose down the leeward or slipface.
a. Barchan
b. Transverse
c. Parabolic
d. Star
Answer: Barchan - limited sand supply
b. Transverse: These dunes are typically long ridges oriented perpendicular to the wind direction; abundant sand supply
c. Parabolic: Parabolic dunes have a U-shape and are formed in areas with vegetation; they also have their tips pointing into the wind, which does not match the description.
d. Star: Star dunes have multiple arms and form in areas with variable wind directions; they do not fit the description of having a gentle windward slope and a steep slipface
A geologist is examining a roche moutonnée in a glaciated valley. The roche moutonnée exhibits a smooth, polished surface on the upstream side and a rough, jagged surface on the downstream side. Which of the following glacial processes best explains the formation of these contrasting surfaces?
A. Abrasion and plucking by glacial ice
B. Frost wedging and solifluction
C. Glacial deposition and moraine formation
D. Ice thrusting and nivation
A. Abrasion and plucking by glacial ice
