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Madrid PAU Geology & Environmental Sciences study materials
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Madrid PAU Geology & Environmental Sciences practice questions

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Question 1Geology, Earth systems, resources, hazards and environmental evidence

Which seismic wave phenomenon accounts for the total absence of direct S-waves on seismograms recorded at angular distances greater than 104° from an earthquake focus?

  1. S-waves cannot propagate through the liquid outer core because fluids lack shear strength. Correct answer.
  2. S-waves undergo refraction and increase in speed, bending upward away from deep stations.
  3. S-waves are converted into high-frequency Rayleigh surface waves at the lithosphere-asthenosphere boundary.
  4. S-waves are completely absorbed by plastic deformation within the solid inner core.

Explanation

Transverse shear waves (S-waves) require a rigid medium with shear strength to propagate. Because the Earth's outer core is molten liquid metal, shear stress cannot be transmitted, creating an S-wave shadow zone beyond 104° from the epicenter.

Question 2Geology, Earth systems, resources, hazards and environmental evidence

A seismograph station records the initial arrival of P-waves at 10:00:00 AM and the initial arrival of S-waves at 10:00:15 AM. Assuming average P-wave velocity v_p = 8.0 km/s and S-wave velocity v_s = 4.0 km/s, what is the distance from the seismograph to the epicenter?

  1. 120 km Correct answer.
  2. 90 km
  3. 150 km
  4. 180 km

Explanation

The distance d is calculated using d = Δt / (1/v_s - 1/v_p). With Δt = 15 s, 1/v_s = 0.25 s/km, and 1/v_p = 0.125 s/km, we get d = 15 / (0.25 - 0.125) = 15 / 0.125 = 120 km.

Question 3Geology, Earth systems, resources, hazards and environmental evidence

How do the compositional divisions of Earth's interior differ from its mechanical (rheological) divisions?

  1. Compositional layers (crust, mantle, core) are defined by chemical composition, whereas mechanical layers (lithosphere, asthenosphere, mesosphere, outer core, inner core) are defined by physical behavior. Correct answer.
  2. Compositional layers are based on rigidity and ductility, while mechanical layers depend entirely on mineral crystal structures.
  3. Mechanical layers represent chemical differentiation during primordial accretion, whereas compositional layers describe thermal convection units.
  4. Compositional layers apply only to oceanic lithosphere, whereas mechanical layers describe continental margins.

Explanation

Earth is chemically divided into crust, mantle, and core based on rock composition and density differences. Rheologically, physical state and rigidity define the mechanical layers: rigid lithosphere, ductile asthenosphere, solid mesosphere, liquid outer core, and solid inner core.

Question 4Geology, Earth systems, resources, hazards and environmental evidence

What physical mechanism generates Earth's main magnetic field according to the geodynamo theory?

  1. Convection currents of molten iron-nickel in the outer core combined with Earth's rotation (Coriolis effect). Correct answer.
  2. Permanent remanent magnetization of iron-rich minerals within the continental lithosphere.
  3. Thermonuclear fusion occurring at the center of the solid inner core.
  4. Piezoelectric currents generated by quartz crystals under extreme pressure in the lower mantle.

Explanation

Earth's geomagnetic field is generated by self-sustaining dynamo action in the liquid outer core, where thermal and compositional convection currents of liquid iron-nickel are organized into spiral columns by the Coriolis force.

Question 5Geology, Earth systems, resources, hazards and environmental evidence

Under the Airy model of isostasy, what root depth r is required beneath a mountain range elevated h = 3.0 km above sea level, assuming average crustal density ρ_c = 2.7 g/cm³ and mantle density ρ_m = 3.3 g/cm³?

  1. 13.5 km Correct answer.
  2. 8.1 km
  3. 18.0 km
  4. 22.5 km

Explanation

Airy isostasy requires hydrostatic balance at the depth of compensation: r = h * (ρ_c / (ρ_m - ρ_c)). Substituting values gives r = 3.0 * (2.7 / (3.3 - 2.7)) = 3.0 * (2.7 / 0.6) = 3.0 * 4.5 = 13.5 km.

Question 6Geology, Earth systems, resources, hazards and environmental evidence

If the mean surface temperature is 15°C and the average continental geothermal gradient is 30°C/km, what temperature is expected at a depth of 4.0 km?

  1. 135°C Correct answer.
  2. 120°C
  3. 150°C
  4. 105°C

Explanation

Temperature at depth d is T = T_surface + (gradient * d). Here, T = 15°C + (30°C/km * 4.0 km) = 15 + 120 = 135°C.

Question 7Geology, Earth systems, resources, hazards and environmental evidence

What major observational discovery in the 1960s provided the key physical mechanism validating continental drift into modern Plate Tectonics?

  1. Symmetrical paleomagnetic stripes recording magnetic reversals on opposite sides of mid-ocean ridges. Correct answer.
  2. Discovery of Mesosaurus fossils in both South America and Africa.
  3. Matching fit of continental shelf boundaries across the Atlantic Ocean.
  4. Glacial striations indicating Carboniferous ice flow directions across Gondwana.

Explanation

The Vine-Matthews-Morley hypothesis proved sea-floor spreading by linking seafloor paleomagnetic stripes to geomagnetic field reversals, providing the quantitative engine driving plate movement.

Question 8Geology, Earth systems, resources, hazards and environmental evidence

Which rock sequence represents an ophiolite suite emplaced onto continental margins during ocean closure?

  1. Deep-sea pelagic sediments, pillow basalts, sheeted dikes, layered gabbros, and mantle peridotites. Correct answer.
  2. Granitic batholiths, ignimbrites, arkosic sandstones, and continental flood basalts.
  3. Limestone reef structures, evaporites, red beds, and quartzites.
  4. Eclogites, blue schists, migmatites, and high-grade regional gneisses.

Explanation

An ophiolite sequence preserves oceanic lithosphere: pelagic sediments (chert/shale) on top, followed by pillow basalts, sheeted dike complex, layered gabbros, and ultramafic mantle tectonites (harzburgite/lherzolite).

Question 9Geology, Earth systems, resources, hazards and environmental evidence

What structural and bathymetric features characterize an oceanic-oceanic convergent subduction zone?

  1. Deep oceanic trench, accretionary wedge, forearc basin, and volcanic island arc. Correct answer.
  2. Central rift valley, high geothermal heat flow, transform faults, and pillow lavas.
  3. Suture zone, broad interior plateau, regional thrust belts, and crustal thickening.
  4. Linear escarpment, horizontal offset streams, sag ponds, and pressure ridges.

Explanation

Subduction of oceanic lithosphere beneath another oceanic plate creates a deep ocean trench where flexure occurs, an accretionary prism of scraped sediment, a forearc basin, and a curved chain of volcanic islands (island arc).

Question 10Geology, Earth systems, resources, hazards and environmental evidence

What defines the Wadati-Benioff zone in subduction geodynamics?

  1. A planar zone of dipping earthquake hypocenters tracing the descending cool oceanic slab into the mantle down to ~670 km. Correct answer.
  2. The horizontal boundary separating the asthenosphere from the lower mantle mesosphere.
  3. The shallow region of partial melting immediately beneath mid-ocean ridge crests.
  4. The low-velocity seismic zone where basaltic magma accumulates in continental crust.

Explanation

The Wadati-Benioff zone is a dipping seismic surface produced by brittle deformation within subducting lithospheric plates, extending from shallow trenches down to the 670 km mantle transition zone.

Question 11Geology, Earth systems, resources, hazards and environmental evidence

Why do continental-continental plate collisions (such as the Himalayas or Pyrenees) produce immense mountain ranges without active deep subduction of continental crust?

  1. Continental crust is rich in quartz and feldspar, giving it low density (~2.7 g/cm³) that resists buoyant subduction into the denser mantle. Correct answer.
  2. Continental rocks are too rigid to undergo ductile shortening or thrust faulting.
  3. Thermal convection in the mantle reverses direction when continents touch.
  4. Water content in continental margins prevents metamorphic mineral phase transitions.

Explanation

Because continental crust has low average density (~2.7 g/cm³) relative to asthenosphere (~3.3 g/cm³), it cannot subduct deeply. Instead, collision causes horizontal crustal shortening, intense folding, and double-thickness mountain uplift.

Question 12Geology, Earth systems, resources, hazards and environmental evidence

Which statement correctly describes transform fault plate boundaries?

  1. Plates slide horizontally past one another along strike-slip faults without generating or destroying lithosphere. Correct answer.
  2. Plates pull apart creating new oceanic lithosphere through decompression melting.
  3. One plate sinks beneath another generating deep-focus earthquakes and calc-alkaline magmatism.
  4. Hot mantle plumes burn through moving lithospheric plates producing volcanic chains.

Explanation

Transform boundaries are conservative plate margins where oceanic or continental plates shear laterally past each other along strike-slip faults, conserving lithospheric mass.

Question 13Geology, Earth systems, resources, hazards and environmental evidence

A stationary mantle plume generates a volcanic seamount chain. If two extinct volcanic seamounts along the track are separated by 450 km and radiometric dating indicates ages of 9.0 million years and 0 (active island) respectively, what is the absolute velocity of the overriding tectonic plate?

  1. 5.0 cm/year Correct answer.
  2. 2.0 cm/year
  3. 10.0 cm/year
  4. 15.0 cm/year

Explanation

Plate velocity v = distance / time = 450 km / 9.0 Ma = (450 * 10^5 cm) / (9.0 * 10^6 yr) = 5.0 cm/year.

Question 14Geology, Earth systems, resources, hazards and environmental evidence

What primary mechanism induces partial melting of mantle peridotite at convergent subduction zone boundaries?

  1. Addition of water and volatile fluids released from dehydrated subducting oceanic sediments lower the mantle solidus temperature (flux melting). Correct answer.
  2. Decompression of rising solid mantle rocks without heat loss (decompression melting).
  3. Direct thermal conduction from outer core boundary superheating the upper mantle.
  4. Frictional heating along strike-slip transform faults melting ambient mantle lithosphere.

Explanation

As oceanic crust subducts, hydrous minerals undergo dehydration. The released H_2O migrates into the overlying mantle wedge, lowering the peridotite solidus temperature and triggering flux melting.

Question 15Geology, Earth systems, resources, hazards and environmental evidence

According to Bowen's Reaction Series, which mineral crystallizes first from a cooling basaltic magma at the highest temperature along the discontinuous branch?

  1. Olivine Correct answer.
  2. Pyroxene (Augite)
  3. Amphibole (Hornblende)
  4. Biotite mica

Explanation

At high temperatures (~1200°C), olivine is the first silicate mineral to crystallize in Bowen's discontinuous series, followed progressively by pyroxene, amphibole, and biotite as temperature drops.

Question 16Geology, Earth systems, resources, hazards and environmental evidence

What distinguishes a dike from a sill in igneous structural geology?

  1. A dike is a discordant intrusive body that cuts across existing rock layers, whereas a sill is a concordant body injected parallel to bedding planes. Correct answer.
  2. A dike forms on Earth's surface as a lava flow, while a sill is an underground plutonic body.
  3. A dike is mushroom-shaped with a flat floor, while a sill is a massive batholith covering over 100 km².
  4. A dike consists exclusively of felsic granite, while a sill consists only of ultramafic peridotite.

Explanation

Dikes cut across preexisting stratification or foliation (discordant geometry), whereas sills intrude horizontally or sub-horizontally parallel to existing rock strata (concordant geometry).

Question 17Geology, Earth systems, resources, hazards and environmental evidence

Why do silica-rich rhyolitic magmas erupt with significantly higher explosive violence than low-silica basaltic magmas?

  1. High silica content creates a highly viscous magma framework that traps dissolved gases until pressure builds up catastrophically. Correct answer.
  2. Rhyolitic magma erupts at much higher temperatures (~1300°C) causing thermal detonation.
  3. Basaltic magmas contain high dissolved water concentrations that suppress gas expansion.
  4. Rhyolitic magmas originate in the mantle core boundary where pressure is extreme.

Explanation

Silica forms polymer chains (tetrahedral networks) that greatly increase magma viscosity. High viscosity prevents dissolved volatiles (H_2O, CO_2) from escaping peacefully, building extreme pressure until explosive fragmentation occurs.

Question 18Geology, Earth systems, resources, hazards and environmental evidence

Which type of metamorphism is primarily driven by high thermal heat around igneous intrusions under low lithostatic pressure, producing non-foliated hornfels rocks?

  1. Contact (thermal) metamorphism Correct answer.
  2. Regional (dynamothermal) metamorphism
  3. Cataclastic (fault-zone) metamorphism
  4. Hydrothermal metamorphism

Explanation

Contact metamorphism occurs when host rocks are baked by heat adjacent to magma intrusions at shallow depths (low pressure), creating un-foliated fine-grained metamorphic rocks called hornfels.

Question 19Geology, Earth systems, resources, hazards and environmental evidence

Which metamorphic facies sequence represents ultra-high pressure (UHP) subduction conditions characteristic of deep slab descent?

  1. Blueschist to Eclogite facies Correct answer.
  2. Zeolite to Greenschist facies
  3. Hornfels to Sanidinite facies
  4. Amphibolite to Granulite facies

Explanation

Subduction zones exhibit low geothermal gradients under high pressures. Rocks progress from Blueschist facies (containing glaucophane) to high-pressure Eclogite facies (containing garnet and omphacitic pyroxene).

Question 20Geology, Earth systems, resources, hazards and environmental evidence

How do brittle and ductile deformation differ when rocks are subjected to tectonic stress?

  1. Brittle deformation results in fracturing and faulting at shallow depths (low T and P), whereas ductile deformation produces folding and flow at deep crustal levels (high T and P). Correct answer.
  2. Brittle deformation causes elastic bending without permanent change, whereas ductile deformation causes immediate rock shattering.
  3. Brittle deformation occurs only under tensional stress, whereas ductile deformation occurs only under shear stress.
  4. Brittle deformation produces slaty cleavage, while ductile deformation produces slickensides.

Explanation

Near Earth's surface (low temperature and lithostatic pressure), stress exceeds rock strength, causing brittle fracturing/faulting. At greater crustal depths, high temperature and pressure cause rocks to yield ductily by permanent folding and plastic flow.

Question 21Geology, Earth systems, resources, hazards and environmental evidence

What geometric displacement defines a normal fault?

  1. The hanging wall moves downward relative to the footwall under tensional stress. Correct answer.
  2. The hanging wall moves upward relative to the footwall under compressional stress.
  3. The fault blocks slide horizontally past each other under shear stress.
  4. The hanging wall rotates around a vertical axis without vertical displacement.

Explanation

Normal faults develop under crustal extension (tensional stress), causing the hanging wall block to move down relative to the footwall block.

Question 22Geology, Earth systems, resources, hazards and environmental evidence

In a eroded structural anticline, where are the oldest stratigraphic rock layers located?

  1. Along the central axial core of the fold. Correct answer.
  2. On the outer limbs furthest from the axial trace.
  3. At the lowest elevation along the plunge direction.
  4. Stratigraphic age cannot be determined from folded structures.

Explanation

An anticline is a convex-upward fold. When truncated by erosion, the oldest strata are exposed at the center (axial core), flanked symmetrically by progressively younger beds on the limbs.

Question 23Geology, Earth systems, resources, hazards and environmental evidence

Which major tectonic event shaped the granitic basement and high-grade metamorphic rocks of the Spanish Central System (Sierra de Guadarrama) in Madrid?

  1. The Variscan (Hercynian) Orogeny during the Late Paleozoic. Correct answer.
  2. The Alpine Orogeny during the Cenozoic.
  3. The Cadomian Orogeny during the Neoproterozoic.
  4. The Atlantic Rifting event during the Mesozoic.

Explanation

The granitic batholiths and gneisses of the Guadarrama range formed during the Variscan (Hercynian) orogeny (~350–290 Ma) through continental collision between Laurussia and Gondwana.

Question 24Geology, Earth systems, resources, hazards and environmental evidence

What metamorphic petrological process forms migmatites at the upper limit of regional metamorphism?

  1. Anatexis (partial melting) of quartz-feldspathic rocks yielding intermixed igneous leucosome and metamorphic melanosome layers. Correct answer.
  2. Complete recrystallization of calcite under low-grade hydrothermal fluids.
  3. Dynamic shearing of basaltic dikes in subduction channels.
  4. Low-temperature hydration of dunite into serpentinite.

Explanation

Migmatites represent the transition between metamorphism and magmatism. Extreme regional temperatures cause high-grade metamorphic rocks to undergo partial melting (anatexis), separating into a granitic melt light band (leucosome) and a dark residual metamorphic band (melanosome).

Question 25Geology, Earth systems, resources, hazards and environmental evidence

According to the logarithmic scaling of seismic wave energy, approximately how many times more energy is released by a magnitude 7.0 earthquake compared to a magnitude 5.0 earthquake?

  1. 1,000 times Correct answer.
  2. 100 times
  3. 32 times
  4. 10,000 times

Explanation

Seismic wave energy E increases by a factor of 10^(1.5 * ΔM). For ΔM = 7.0 - 5.0 = 2.0, the energy ratio is 10^(1.5 * 2) = 10^3 = 1,000 times.

Question 26Geology, Earth systems, resources, hazards and environmental evidence

Which physical weathering mechanism is most dominant in high-mountain periglacial environments such as the Sierra de Guadarrama summit zone?

  1. Frost wedging (gelifraction / freeze-thaw expansion of water in rock fractures). Correct answer.
  2. Thermal stress fatigue due to desert diurnal temperature swings.
  3. Salt haloclasty due to coastal sea-spray evaporation.
  4. Hydrolysis of plagioclase feldspars into kaolinite clay.

Explanation

In high alpine and periglacial zones, repeated diurnal freeze-thaw cycles cause water trapped in micro-cracks to expand by ~9% upon freezing, exerting immense pressure that shatters rocks into scree slopes (talus).

Question 27Geology, Earth systems, resources, hazards and environmental evidence

What chemical reaction occurs during the hydrolysis of potassium feldspar (orthoclase) by carbonated water?

  1. Orthoclase reacts with carbonic acid and water to yield soluble potassium ions, bicarbonate ions, silica, and kaolinite clay. Correct answer.
  2. Orthoclase directly dissolves into calcium carbonate and carbon dioxide gas.
  3. Orthoclase oxidizes upon contact with atmospheric oxygen, precipitating hematite.
  4. Orthoclase absorbs water molecules into its crystal lattice without changing chemical bonding.

Explanation

Hydrolysis replaces K+ cations in orthoclase (KAlSi_3O_8) with H+ ions from carbonic acid, transforming the framework silicate into insoluble kaolinite clay Al_2Si_2O_5(OH)_4 while releasing K+, HCO_3-, and H_4SiO_4 into solution.

Question 28Geology, Earth systems, resources, hazards and environmental evidence

In a mature soil profile (edaphic horizonation), which horizon is designated as the zone of max accumulation (illuviation) of leached clays, iron, and aluminum oxides?

  1. B horizon Correct answer.
  2. A horizon
  3. E horizon
  4. O horizon

Explanation

The B horizon (subsoil) is the illuvial zone where soluble minerals, clays, and sesquioxides leached downward from upper horizons accumulate.

Question 29Geology, Earth systems, resources, hazards and environmental evidence

A undisturbed soil core has a total bulk volume V_t = 100 cm³ and a dry mass m_d = 135 g. Assuming an average mineral particle density ρ_p = 2.7 g/cm³, what is the total porosity n of this soil?

  1. 50% Correct answer.
  2. 35%
  3. 27%
  4. 65%

Explanation

Bulk density ρ_b = m_d / V_t = 135 / 100 = 1.35 g/cm³. Porosity n = 1 - (ρ_b / ρ_p) = 1 - (1.35 / 2.7) = 1 - 0.50 = 0.50 or 50%.

Question 30Geology, Earth systems, resources, hazards and environmental evidence

A slope stability analysis evaluates a potential sliding plane where the resisting shear strength S_r is calculated as 150 kPa and the driving shear stress τ along the plane is 100 kPa. What is the Factor of Safety (FS) and what does it indicate about slope stability?

  1. FS = 1.5; the slope is stable against failure. Correct answer.
  2. FS = 0.67; the slope is actively failing.
  3. FS = 1.0; the slope is at critical equilibrium.
  4. FS = 2.5; the slope is over-consolidated.

Explanation

The Factor of Safety is FS = Resisting Strength / Driving Stress = S_r / τ = 150 kPa / 100 kPa = 1.5. Since FS > 1.0, resisting forces exceed driving forces, making the slope stable.

Question 31Geology, Earth systems, resources, hazards and environmental evidence

In a drainage basin hydrological water budget under steady-state groundwater storage (ΔS = 0), if annual mean precipitation P is 900 mm and evapotranspiration ET is 550 mm, what is the expected annual surface and subsurface runoff R?

  1. 350 mm Correct answer.
  2. 1,450 mm
  3. 450 mm
  4. 250 mm

Explanation

The hydrological budget equation is P = ET + R + ΔS. With ΔS = 0, total runoff R = P - ET = 900 mm - 550 mm = 350 mm.

Question 32Geology, Earth systems, resources, hazards and environmental evidence

According to the Hjulström diagram governing sediment transport, why does fine clay (<0.002 mm) require higher stream flow velocities to initiate erosion than medium sand (0.2–0.5 mm)?

  1. Inter-particle electrostatic forces (cohesion) between microscopic clay minerals tightly bind the clay bed. Correct answer.
  2. Clay grains have a higher specific gravity than quartz sand grains.
  3. Clay particles form dense gravel conglomerates on the riverbed.
  4. Laminar flow sublayers shield sand grains while exposing clay to turbulent eddies.

Explanation

Although individual clay particles are tiny, cohesive electrostatic forces (van der Waals and hydrogen bonding) between clay minerals bind them into a sticky matrix that resists entrainment, requiring higher critical velocity to erode than non-cohesive sand.

Question 33Geology, Earth systems, resources, hazards and environmental evidence

Which fluvial geomorphic process drives the formation and eventual cutoff of an oxbow lake in a meandering river system?

  1. Lateral erosion along the outer cutbank combined with sediment deposition along the inner point bar. Correct answer.
  2. Vertical headward incision down to bedrock base level.
  3. Tectonic uplift of the floodplain during flood discharge.
  4. Subsurface dissolution of underlying limestone strata.

Explanation

Meanders migrate because helicoidal flow causes high-velocity erosion on the outer riverbank (cutbank) and low-velocity deposition on the inner bank (point bar). Narrow meander necks are eventually breached during floods, isolating the loop into an oxbow lake.

Question 34Geology, Earth systems, resources, hazards and environmental evidence

A stream channel with a rectangular cross-section has a channel width w = 10.0 m, average water depth d = 2.0 m, and average mean flow velocity v = 1.5 m/s. What is the river discharge Q?

  1. 30.0 m³/s Correct answer.
  2. 15.0 m³/s
  3. 20.0 m³/s
  4. 45.0 m³/s

Explanation

Discharge Q is calculated as cross-sectional area times flow velocity: Q = A * v = (w * d) * v = (10.0 m * 2.0 m) * 1.5 m/s = 20.0 m² * 1.5 m/s = 30.0 m³/s.

Question 35Geology, Earth systems, resources, hazards and environmental evidence

Which sequence of karst geomorphic surface depressions represents progressive coalescent dissolution from smallest to largest structural scale?

  1. Lapiez -> Doline (sinkhole) -> Uvala -> Polje Correct answer.
  2. Polje -> Uvala -> Doline -> Lapiez
  3. Doline -> Lapiez -> Polje -> Uvala
  4. Uvala -> Polje -> Lapiez -> Doline

Explanation

Karst surface dissolution begins with micro-grooves (lapiez), progresses to closed circular sinkholes (dolines), coalesces into compound depressions (uvalas), and culminates in massive flat-bottomed structural karst valleys (poljes).

Question 36Geology, Earth systems, resources, hazards and environmental evidence

What chemical equilibrium process forms stalactites and stalagmites inside limestone caves?

  1. Degassing of dissolved CO₂ from percolating seepage water into cave air causes precipitation of calcium carbonate (CaCO₃). Correct answer.
  2. Evaporation of sulfuric acid solutions leaves behind insoluble silica residue.
  3. Oxidation of ferrous iron forms ferric hydroxide dripstones.
  4. Freezing of underground groundwater streams precipitates ice speleothems.

Explanation

Groundwater charged with CO₂ dissolves limestone above. Upon entering a cave chamber with lower partial pressure of CO₂, CO₂ degasses from droplets into the air. This shifts the reaction CaCO₃ + H₂O + CO₂ <-> Ca²⁺ + 2HCO₃⁻ to the left, precipitating calcite (CaCO₃).

Question 37Geology, Earth systems, resources, hazards and environmental evidence

Which alpine glacial erosion landform is described as a sharp, pyramid-shaped mountain peak bounded by three or more intersecting glacial cirque walls?

  1. Horn (e.g. Matterhorn or Peñalara peak features) Correct answer.
  2. Arête
  3. Cirque
  4. Esker

Explanation

A glacial horn is a steep pyramid peak formed by headward plucking and erosion of three or more glaciers carving cirques around a single mountain mountain massif.

Question 38Geology, Earth systems, resources, hazards and environmental evidence

Which aeolian sand dune geometry is crescent-shaped with horns pointing downwind in areas with limited sand supply and constant unidirectional wind?

  1. Barchan dune Correct answer.
  2. Transverse dune
  3. Star dune
  4. Parabolic dune

Explanation

Barchan dunes are solitary, crescent-shaped dunes facing unidirectional winds; their tips (horns) point downwind because sand moves faster around the margins than over the thick center.

Question 39Geology, Earth systems, resources, hazards and environmental evidence

What coastal engineering and geomorphic phenomenon occurs when oblique wave approach drives zigzag sediment transport along a shoreline?

  1. Longshore drift (littoral drift) Correct answer.
  2. Wave refraction convergence
  3. Tidal surge flooding
  4. Submarine canyon slumping

Explanation

Waves approaching the coast at an oblique angle push sediment up the beach face via swash, while backwash pulls sediment perpendicular to the shore, creating net longitudinal transport called longshore drift.

Question 40Geology, Earth systems, resources, hazards and environmental evidence

What landform feature results when longshore transport builds a sand spit completely connecting an offshore island to the mainland coast?

  1. Tombolo Correct answer.
  2. Barrier island
  3. Wave-cut platform
  4. Estuary bar

Explanation

A tombolo is a sand ridge or spit deposited by wave wave refraction and longshore drift that connects an island to the mainland.

Question 41Geology, Earth systems, resources, hazards and environmental evidence

What defines the water table in physical groundwater hydrology?

  1. The upper boundary of the phreatic (saturated) zone where pore water pressure equals atmospheric pressure. Correct answer.
  2. The boundary between continental crust bedrock and sedimentary cover.
  3. The base of the unconfined aquifer where clay aquitards completely block flow.
  4. The maximum depth to which capillary water rises above plant root systems.

Explanation

The water table is the surface separating the unsaturated vadose zone above from the fully saturated phreatic zone below, defined mechanically where fluid pore pressure equals atmospheric pressure.

Question 42Geology, Earth systems, resources, hazards and environmental evidence

Using Darcy's Law Q = K * A * (dh/dl), calculate the daily groundwater discharge Q through a confined sandstone aquifer with hydraulic conductivity K = 20.0 m/day, cross-sectional area A = 500.0 m², and hydraulic gradient dh/dl = 0.01.

  1. 100.0 m³/day Correct answer.
  2. 10.0 m³/day
  3. 1,000.0 m³/day
  4. 50.0 m³/day

Explanation

Using Darcy's formula: Q = K * A * i = 20.0 m/day * 500.0 m² * 0.01 = 10,000 * 0.01 = 100.0 m³/day.

Question 43Geology, Earth systems, resources, hazards and environmental evidence

Which desert geomorphic landform consists of a broad, gently sloping erosional bedrock surface extending out from the base of a retreating mountain front in arid regions?

  1. Pediment Correct answer.
  2. Playa lake
  3. Bajada
  4. Wadi

Explanation

A pediment is a gently inclined erosional bedrock surface carved by lateral planation and sheetwash along mountain fronts in arid to semi-arid environments.

Question 44Geology, Earth systems, resources, hazards and environmental evidence

Using the Universal Soil Loss Equation (USLE: A = R * K * L * S * C * P), calculate annual soil loss A in tonnes/ha/yr for a site with rainfall erosivity R = 100, soil erodibility K = 0.30, topographic factor LS = 2.0, cover management C = 0.50, and support practice P = 1.0.

  1. 30.0 tonnes/ha/year Correct answer.
  2. 15.0 tonnes/ha/year
  3. 60.0 tonnes/ha/year
  4. 300.0 tonnes/ha/year

Explanation

Applying USLE multiplication: A = 100 * 0.30 * 2.0 * 0.50 * 1.0 = 30 * 1.0 = 30.0 tonnes/ha/year.

Question 45Geology, Earth systems, resources, hazards and environmental evidence

What geomorphic landscape zone is defined by freeze-thaw cycles, permafrost, solifluction lobes, and patterned ground?

  1. Periglacial morphoclimatic zone Correct answer.
  2. Arid morphoclimatic zone
  3. Tropical morphoclimatic zone
  4. Temperate maritime zone

Explanation

Periglacial environments surround glacial zones where non-glacial frost action, permafrost thawing, active layer solifluction, and cryoturbation build patterned ground.

Question 46Geology, Earth systems, resources, hazards and environmental evidence

Which criteria must be strictly satisfied for a substance to be scientifically classified as a mineral?

  1. Naturally occurring, inorganic, solid, orderly crystalline internal structure, and definite chemical composition. Correct answer.
  2. Synthetically produced in laboratories, liquid or solid, amorphous, variable composition.
  3. Organic origin, solid, homogeneous, crystal lattice absent.
  4. Naturally occurring, metallic, liquid at room temperature, crystalline.

Explanation

Geological definition of a mineral requires five criteria: naturally occurring, inorganic, solid state, orderly crystalline atomic arrangement, and definite (or bounded variable) chemical composition.

Question 47Geology, Earth systems, resources, hazards and environmental evidence

Which mineral on the Mohs hardness scale is defined as standard reference index 7?

  1. Quartz Correct answer.
  2. Orthoclase feldspar
  3. Topaz
  4. Fluorite

Explanation

Mohs hardness scale ranks minerals 1 to 10: 1-Talc, 2-Gypsum, 3-Calcite, 4-Fluorite, 5-Apatite, 6-Orthoclase, 7-Quartz, 8-Topaz, 9-Corundum, 10-Diamond.

Question 48Geology, Earth systems, resources, hazards and environmental evidence

How are silica tetrahedra [SiO₄]⁴⁻ arranged in phyllosilicate minerals such as micas (biotite, muscovite) and clay minerals?

  1. Continuous 2D sheets formed by sharing 3 oxygen atoms between adjacent tetrahedra. Correct answer.
  2. Isolated individual tetrahedra bonded only by interstitial metal cations (nesosilicates).
  3. Single 1D linear chains sharing 2 oxygen atoms (inosilicates).
  4. Fully interconnected 3D frameworks sharing all 4 oxygen atoms (tectosilicates).

Explanation

Phyllosilicates (sheet silicates) share 3 corner oxygen atoms per silica tetrahedron, creating 2D sheets that give micas and clays their perfect basal cleavage.

Question 49Geology, Earth systems, resources, hazards and environmental evidence

Which non-silicate mineral group includes gypsum (CaSO₄·2H₂O), a major evaporite resource heavily mined in the Madrid Basin?

  1. Sulfates Correct answer.
  2. Carbonates
  3. Halides
  4. Sulfides

Explanation

Gypsum is a hydrated calcium sulfate mineral belonging to the sulfate group (SO₄²⁻ anion), formed by evaporitic precipitation in saline lacustrine basins such as the Tertiary Madrid basin.

Question 50Geology, Earth systems, resources, hazards and environmental evidence

Which pair of igneous rocks represents coarse-grained plutonic and fine-grained volcanic equivalents of felsic magma composition?

  1. Granite (plutonic) and Rhyolite (volcanic) Correct answer.
  2. Gabbro (plutonic) and Basalt (volcanic)
  3. Diorite (plutonic) and Andesite (volcanic)
  4. Peridotite (plutonic) and Komatiite (volcanic)

Explanation

Granite and rhyolite are high-silica (>65% SiO₂) felsic rocks rich in quartz and potassium feldspar. Granite crystallizes slowly underground (phaneritic plutonic), whereas rhyolite cools rapidly on the surface (aphanitic volcanic).