XVI. Questions (426-450) Flashcards
A crescent-shaped dune with limbs upwind is called a
a) parabolic or blowout dune
b) barchan
c) croissant
d) transverse dune
e) longitudinal dune
a) parabolic or blowout dune
Parabolic dunes (or blowout dunes) are crescent-shaped dunes with their limbs pointing upwind, commonly formed in areas with vegetation that stabilizes parts of the dune while the center gets blown out.
A crescent-shaped sand dune is called:
a. Wind arch
b. Barchan
c. Arch ridge
d. Moon ridge
b. Barchan
A cross section with a vertical scale of 1cm = 125 m drawn from a 1:25,000 scale topographic map would have a vertical exaggeration of: ____________.
a. 1.5 x
b. 2 x
c. 2.5 x
d. 3x
e. none of the above
b. 2 x
A dating method for obsidian artifacts based on the phenomenon of obsidian’s absorbing water at the rate dependent on its chemical composition and the ambient temperature is known as
a. obsi-hydraulic dating
b. hydration layer dating
c. hydrobsidian dating
d. aquatic magnetostratigraphy
b) hydration layer dating
Obsidian hydration dating is a geochemical method used to determine the age of obsidian artifacts. It is based on the phenomenon that obsidian absorbs water from its environment at a predictable rate, forming a hydration layer whose thickness can be measured to estimate the time since the artifact’s surface was freshly exposed.
A debris flow that has water content sufficient to make it fluid is commonly called
a. Earthflow
b. Creep
c. Debris flow
d. Mudflow
e. none of the above
d) Mudflow
A mudflow is a type of mass wasting where a mixture of water and soil or debris becomes fluid enough to flow downhill rapidly. It typically has a high water content, which reduces friction and allows the flow to move like a liquid. Mudflows are common in areas with loose, unconsolidated material and heavy rainfall.
A deep ocean sediment consisting of at least 30% skeletal
remains of once floating microorganisms
o pelagic ooze
o glauconite
o dolostone
o coquina
o pelagic ooze
Pelagic ooze is a type of deep-sea sediment that contains at least 30% of the skeletal remains of microorganisms, such as foraminifera, diatoms, radiolarians, or coccolithophores. These microscopic organisms accumulate on the ocean floor after they die, forming extensive deposits over time. Pelagic oozes can be either calcareous (rich in calcium carbonate) or siliceous (rich in silica), depending on the dominant type of microorganism.
A deformation that is, if the stress is withdrawn, the body returns to its original shape and size.
a. Elastic
b. Plastic
c. Rupture
d. None of the above
a. Elastic
Elastic deformation occurs when a material deforms under stress but returns to its original shape and size once the stress is removed. This behavior is typical of materials within their elastic limit, where the relationship between stress and strain follows Hooke’s law.
A dendritic pattern exhibited by a fluvial system in an area likely suggests the presence of:
a. Resistant and non-resistant rock
b. Rocks of equal resistance to weathering
c. Volcanic centers
d. A and C
e. B and C
b. Rocks of equal resistance to weathering
A dense mass of water on smoke or dust particles in the lower atmospheric layers constitute
a) Fog
b) Mist
c) Frost
d) Blizzard
a) Fog
A deposit formed from the effects of heat and accession of an igneous body to the surrounding rocks
(a) intrusion
(b) vein
(c) contact metamorphism
(d) chilled margins
(e) contact metasomatism
(c) contact metamorphism
Contact metamorphism occurs when surrounding rocks are altered by the heat from an intruding igneous body. The high temperature, often combined with the introduction of fluids from the magma, leads to the recrystallization and mineralogical changes of the host rock, forming a metamorphic aureole around the intrusion.
A depression much larger than the original crater, formed when the volcano collapses into an empty magma chamber is called:
- vent
- caldera
- basin
- schism
- rift
- caldera
A caldera is a large, basin-like depression that forms when a volcano collapses into an emptied magma chamber after a major eruption. Calderas are typically much larger than the original volcanic crater and can span several kilometers in diameter. They often become filled with water, forming caldera lakes.
A depression produced by subsidence along faults.
(a) lake
(b) trench
(c) graben
(c) graben
A graben is a depressed block of the Earth’s crust bounded by parallel faults, where the land between the faults has subsided relative to the surrounding areas. It typically forms in regions experiencing extensional tectonics, where the crust is being pulled apart. Graben structures are often associated with rift valleys and fault-block mountain ranges.
A deviation from uniformity in physical properties or a perturbation from a normal, uniform, or predictable field is a :
a. geophysical anomaly
b. nonconformity
c. anomalous background
d. background value
e. none of the above
a. geophysical anomaly
A geophysical anomaly is a deviation from the normal or expected physical properties of the Earth’s subsurface, such as variations in gravity, magnetism, electrical conductivity, or seismic velocity. These anomalies are often indicative of variations in rock types, mineral deposits, fault zones, or other geological features and are crucial in mineral exploration and geophysical surveys.
A dinosaur fossil park designated a World Heritage Site has been established where in the world?
a. Saketi in Himachal Pradesh
b. Alberta, Canada
c. Mammoth Cave, Kentucky, USA
d. Yosemite, California, USA
b. Alberta, Canada
A dip-slip fault in which the hanging wall appeared to have moved down with respect to the footwall. Also known as gravity fault. It is mostly associated with extensional stresses.
(a) normal
(b) thrust
(c) 0blique-slip fault
(a) normal
A normal fault is a type of dip-slip fault where the hanging wall moves downward relative to the footwall. This type of fault is associated with extensional stress, where the crust is being pulled apart. Normal faults are commonly found in regions experiencing tectonic extension, such as rift valleys and divergent plate boundaries. It is also known as a gravity fault because the downward movement of the hanging wall is driven by gravity.
A direct consequence of the opening of the South China Sea is the separation of a microcontinental block from mainland Asia which corresponds today to
A. Palawan
B. Cagayan de Sulu Ridge
C. Scarborough Seamounts
D. Benham Rise
A. Palawan
A disconformity can develop over:
a. An eroded tilted sandstone
b. An eroded horizontal limestone bed
c. An eroded lava flow
d. A and b
e. B and c
e. B and c
A disconformity is an unconformity where sedimentary rock layers are parallel to each other, but there is a gap in the geologic record due to erosion or non-deposition. It forms between horizontal layers of sedimentary rock.
Therefore:
B. An eroded horizontal limestone bed can develop a disconformity because it involves parallel sedimentary layers with an erosion surface between them.
C. An eroded lava flow can also develop a disconformity if subsequent sedimentary layers are deposited on top of it without significant tilting or deformation.
A. An eroded tilted sandstone would instead develop an angular unconformity because the tilted layers are overlain by younger, horizontal layers.
A distinct negative Eu anomaly in a chondrite normalized spidergram is commonly associated with the presence of _____ in the source.
A. plagioclase
B. olivine
C. garnet
D. orthopyroxene
A. plagioclase
A distinct negative Eu anomaly in a chondrite-normalized spidergram typically indicates the presence of plagioclase in the source rock. This is because europium (Eu) can substitute for calcium (Ca) in the crystal structure of plagioclase, especially in Ca-rich plagioclase (like anorthite). During partial melting or crystallization, Eu tends to be incorporated into plagioclase, depleting the melt in Eu and resulting in a negative Eu anomaly in the residual melt or rock.
A divisional planes or surfaces that devides rocks, and along which those has been no visible movement parallel to the plane or surfaces.
Joints
Joints are divisional planes or surfaces in rocks along which there has been no visible movement parallel to the plane or surface. They are natural fractures or separations in rocks that occur without significant displacement. Joints are typically formed due to stress, such as tectonic forces, cooling, or unloading. Unlike faults, joints do not show any appreciable displacement or movement along the fracture surface.
A doctrine that believed the Earth was shaped primarily by great catastrophes?
Catastrophism
A dome or anticlinal sedimentary fold structure formed on top of salt or igneous intrusions
o diapir
o laccolith
o shield
o mesa
o diapir
A diapir is a dome or anticlinal structure formed when a more mobile and ductile material, such as salt or magma, pierces through overlying rock layers. Salt diapirs, also known as salt domes, commonly form in sedimentary basins where thick layers of evaporite minerals (like halite) are buried under more rigid sedimentary rocks. Due to their lower density and plastic behavior, salt masses rise through overlying rock strata, creating a dome-shaped or anticlinal structure.
A domestic extension into rocks above a batholiths is called
a. Cupola
b. Roof pendant
c. Stock
d. Lopolith
e. Diatreme
a. Cupola
A cupola is a dome-shaped or small, rounded protrusion of intrusive igneous rock that extends from the upper surface of a batholith into the overlying country rock. It represents a local upward extension of the batholith, often forming a smaller, isolated mass of igneous rock above the main intrusive body.
A down-dropped block, bounded by parallel normal faults, is termed:
a. geosyncline
b. a graben
c. an overthrust
d. a horst
b. a graben
A graben is a down-dropped block of the Earth’s crust that is bounded by parallel normal faults. It forms when the crust is stretched and pulled apart, causing the central block to sink relative to the adjacent blocks. Grabens are commonly found in regions of extensional tectonics, such as rift valleys.
A downward displacement of surface material caused by natural or artificial removal of underlying support is called:
a) mass movement
b) creep
c) subsidence
d) landslide
c) subsidence
Subsidence is the downward displacement or sinking of the Earth’s surface, caused by the removal or collapse of underlying support. It can result from natural processes, such as the dissolution of soluble rocks (like limestone) or the compaction of sediments, as well as human activities, like groundwater extraction, mining, or oil and gas production.
A drainage basin is underlain by a sandstone cemented by calcium carbonate and underlain by a shale. What might one find in solution in waters of the stream that drains this basin?
A) Calcium ions;
B) Mud;
C) Sand;
D) Sandstone boulders
A) Calcium ions
Since the sandstone is cemented by calcium carbonate (CaCO₃), the stream water that drains the basin is likely to contain calcium ions (Ca²⁺) dissolved from the sandstone. The dissolution of calcium carbonate occurs through chemical weathering, especially in the presence of slightly acidic water (like rainwater containing carbonic acid).
The underlying shale may also contribute fine particles (mud) to the stream, but since the question specifically asks about what might be found in solution, calcium ions are the correct answer.
