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Question 1

What are the five criteria that define a mineral?

Answer 1

Naturally occurring, inorganic, solid, orderly crystalline structure, definite chemical composition.

Question 2

Name the property measured by scratching a mineral against a porcelain plate.

Answer 2

Streak (color of the mineral’s powder).

Question 3

Which mineral is number 7 on the Mohs hardness scale?

Answer 3

Quartz.

Question 4

What type of silicate structure does olivine have?

Answer 4

Isolated (independent) tetrahedra.

Question 5

Define polymorph and give an example pair.

Answer 5

Minerals with same composition but different crystal structure; example: diamond and graphite (both C).

Question 6

Which test distinguishes calcite from quartz quickly?

Answer 6

Reaction with dilute hydrochloric acid (calcite effervesces).

Question 7

Luster describes how a mineral reflects light. What are the two broad categories?

Answer 7

Metallic and non‑metallic.

Question 8

What element makes a mineral ferromagnesian?

Answer 8

Presence of iron (Fe) and/or magnesium (Mg).

Question 9

Intrusive igneous rocks cool ______ and have ______ crystals.

Answer 9

Slowly; large (coarse‑grained, phaneritic).

Question 10

Name the ultramafic intrusive rock composed mostly of olivine and pyroxene.

Answer 10

Peridotite.

Question 11

What is Bowen’s Reaction Series?

Answer 11

A sequence that shows the order minerals crystallize from a mafic magma as it cools.

Question 12

Which igneous texture indicates two stages of cooling?

Answer 12

Porphyritic (large phenocrysts in fine groundmass).

Question 13

Felsic lavas are more viscous because they are rich in ______.

Answer 13

Silica (SiO₂).

Question 14

Define partial melting.

Answer 14

Process where only a portion of a solid rock melts, producing magma enriched in lower‑melting components.

Question 15

What plate boundary commonly generates basaltic oceanic crust?

Answer 15

Divergent (mid‑ocean ridges).

Question 16

Name the gas that is usually the most abundant in volcanic emissions.

Answer 16

Water vapor (H₂O).

Question 17

Composite volcanoes are also called ______ volcanoes.

Answer 17

Stratovolcanoes.

Question 18

Which volcanic hazard can travel >100 km/h and exceed 800 °C?

Answer 18

Pyroclastic flow (nuee ardente).

Question 19

Hotspot tracks like the Hawaiian–Emperor chain record what?

Answer 19

Direction and speed of plate motion over a stationary mantle plume.

Question 20

What determines whether a volcanic eruption is explosive or effusive?

Answer 20

Magma viscosity and dissolved gas content.

Question 21

Name the tectonic setting of the Andes Mountains.

Answer 21

Oceanic–continental convergent (subduction) boundary.

Question 22

At what depth does wet mantle peridotite typically melt to form arc magmas?

Answer 22

~100 km where water lowers melting temperature.

Question 23

Define lahar.

Answer 23

Mudflow composed of volcanic ash and water, often along river valleys.

Question 24

Which type of plate boundary is associated with transform faults like the San Andreas?

Answer 24

Transform boundary (plates slide laterally).

Question 25

What two processes turn loose sediment into sedimentary rock?

Answer 25

Compaction and cementation (lithification).

Question 26

Arkose is a sandstone rich in ______ grains.

Answer 26

Feldspar.

Question 27

Name the sedimentary structure produced by currents that indicates flow direction.

Answer 27

Cross‑bedding (or ripple marks).

Question 28

Chemical weathering of feldspar produces which clay mineral?

Answer 28

Kaolinite.

Question 29

What is the suspended load of a stream?

Answer 29

Fine particles (silt, clay) carried within the water column.

Question 30

Define soil horizon 'O'.

Answer 30

Organic‑rich layer of decomposed plant material at the surface.

Question 31

Evaporite rock composed mainly of halite is called ______.

Answer 31

Rock salt.

Question 32

Which principle states that layers of sediment are originally deposited horizontally?

Answer 32

Principle of Original Horizontality (Steno).

Question 33

What is the parent rock of marble?

Answer 33

Limestone or dolostone.

Question 34

Name the foliated metamorphic rock with visible mica flakes aligned but no segregation of minerals.

Answer 34

Schist.

Question 35

Contact metamorphism produces a zone called a ______ around an intrusion.

Answer 35

Metamorphic aureole (hornfelsic zone).

Question 36

Which radioactive parent–daughter pair is commonly used to date very old igneous rocks?

Answer 36

Uranium‑238 to Lead‑206.

Question 37

Principle that fragments in a rock unit are older than the unit itself.

Answer 37

Principle of Inclusions.

Question 38

Define unconformity.

Answer 38

A surface representing a gap in the geologic record due to non‑deposition or erosion.

Question 39

Index mineral indicating high metamorphic grade in pelitic rocks.

Answer 39

Sillimanite.

Question 40

What is half‑life?

Answer 40

Time required for half the atoms of a radioactive isotope to decay to daughter products.

Question 41

Who proposed continental drift and the supercontinent Pangaea?

Answer 41

Alfred Wegener.

Question 42

Pattern of ______ reversals recorded in ocean basalt helped confirm seafloor spreading.

Answer 42

Magnetic polarity.

Question 43

Average thickness of continental crust vs oceanic crust.

Answer 43

~35–70 km (continental) vs ~7 km (oceanic).

Question 44

What is a Wadati‑Benioff zone?

Answer 44

Inclined plane of deep earthquakes tracing a subducting slab.

Question 45

Name the soft, ductile layer on which plates move.

Answer 45

Asthenosphere.

Question 46

Transform boundaries conserve lithosphere. Give an oceanic example.

Answer 46

Mid‑Atlantic Ridge fracture zones (e.g., Charlie‑Gibbs).

Question 47

Heat‑driven convection in the mantle is a key ______ force.

Answer 47

Plate‑driving (slab pull and ridge push involved).

Question 48

How old is the oldest oceanic crust on Earth?

Answer 48

< 200 Ma (due to subduction recycling).

Question 49

Name the two main types of seismic body waves.

Answer 49

P‑waves (compressional) and S‑waves (shear).

Question 50

S‑waves do not travel through what part of Earth?

Answer 50

Liquid outer core.

Question 51

The boundary between crust and mantle is called the ______.

Answer 51

Mohorovičić discontinuity (Moho).

Question 52

What causes the P‑wave shadow zone between ~103° and 142° from an earthquake?

Answer 52

Refraction at the core‑mantle boundary due to slower wave speeds in the outer core.

Question 53

Seismic velocity generally ______ with depth in the mantle.

Answer 53

Increases (due to pressure and phase changes).

Question 54

Isostasy explains that thicker crust floats ______ into the mantle.

Answer 54

Deeper.

Question 55

What geophysical method maps variations in gravity field caused by density contrasts?

Answer 55

Gravimetry (gravity surveys).

Question 56

Heat flow highest at mid‑ocean ridges is evidence for ______.

Answer 56

Active upwelling and new crust formation (seafloor spreading).

Question 57

Point inside Earth where earthquake rupture starts.

Answer 57

Hypocenter (focus).

Question 58

Moment magnitude (Mw) is calculated using what three parameters?

Answer 58

Fault area × average slip × rock rigidity (shear modulus).

Question 59

Law describing exponential decay of amplitude with distance.

Answer 59

Attenuation (energy dissipates as waves radiate).

Question 60

Liquefaction occurs in _____, water‑saturated granular sediment during strong shaking.

Answer 60

Loose (unconsolidated) sediment.

Question 61

What instrument records ground motion?

Answer 61

Seismograph (seismometer + recorder).

Question 62

Elastic rebound theory states stress accumulates until rocks break, then they _____ to an undeformed shape.

Answer 62

Snap back (rebound).

Question 63

Earthquakes at depths >300 km occur only at ______ boundaries.

Answer 63

Subduction zones (down‑going slab).

Question 64

Seismic gaps—long quiet segments of faults—may indicate what?

Answer 64

Areas where stress is building, posing risk of future large earthquakes.

Question 65

Difference between brittle and ductile deformation.

Answer 65

Brittle—fracture; ductile—flow/fold without breaking.

Question 66

Hanging wall moves up relative to footwall in a ______ fault.

Answer 66

Reverse.

Question 67

Large‑scale folds with non‑parallel limbs are called ______ folds.

Answer 67

Recumbent.

Question 68

Regional mountain belts often thicken crust, leading to ______ rebound when erosion removes weight.

Answer 68

Isostatic (gravitational) rebound.

Question 69

Horsts and grabens form in what tectonic setting?

Answer 69

Extensional (rifting).

Question 70

Fracture with no significant displacement.

Answer 70

Joint.

Question 71

What is a klippe?

Answer 71

Isolated remnant of a thrust sheet separated by erosion.

Question 72

Stress that squeezes rock is called ______ stress.

Answer 72

Compressional.

Question 73

Slow, imperceptible downslope movement that bends tree trunks is called ______.

Answer 73

Creep.

Question 74

Angle of repose for dry sand is approximately ______ degrees.

Answer 74

30–34 °.

Question 75

Formula for stream discharge (Q).

Answer 75

Q = channel width × depth × velocity.

Question 76

Cut bank forms on the _____ side of a meander bend.

Answer 76

Outside (erosional).

Question 77

Name the flat area bordering a stream and subject to floods.

Answer 77

Floodplain.

Question 78

Alluvial fan develops where a high‑gradient stream ______.

Answer 78

Emerges onto a flatter valley or basin and loses carrying capacity.

Question 79

During heavy rain, why can saturated soil trigger landslides?

Answer 79

Pore‑water pressure reduces friction and cohesion.

Question 80

Stream competence refers to the ______ particle size a river can transport.

Answer 80

Maximum (largest).

Question 81

Zone where rapid temperature decrease with depth occurs.

Answer 81

Thermocline.

Question 82

What causes spring tides?

Answer 82

Alignment of Sun‑Earth‑Moon during full or new moon (constructive gravitational forces).

Question 83

Longshore drift moves sediment ______ to the shoreline.

Answer 83

Parallel (along the coast).

Question 84

A drowned river valley modified by marine processes is called a ______.

Answer 84

Estuary.

Question 85

Stacked, pillow‑shaped basalts indicate eruption ______.

Answer 85

Underwater (mid‑ocean ridge or seafloor).

Question 86

Name three agents that generate ocean surface waves.

Answer 86

Wind speed, wind duration, fetch (distance).

Question 87

Barrier islands migrate landward during sea‑level rise via ______.

Answer 87

Overwash and landward sand transport.

Question 88

Ekman transport moves surface water 90° to wind direction because of ______.

Answer 88

Coriolis effect + friction spiral.

Question 89

Aquifer confined between two aquitards is called ______.

Answer 89

Confined aquifer (artesian).

Question 90

Darcy’s Law formula for groundwater flow rate (Q).

Answer 90

Q = ‑KA (dh/dl) where K = hydraulic conductivity, A = area, dh/dl = hydraulic gradient.

Question 91

Hard water contains high concentrations of ______ ions.

Answer 91

Calcium (Ca²⁺) and magnesium (Mg²⁺).

Question 92

Cone of depression can cause what saltwater‑related problem in coastal wells?

Answer 92

Saltwater intrusion as freshwater lens is drawn down.

Question 93

Term for land surface sinking due to groundwater withdrawal.

Answer 93

Subsidence.

Question 94

Karst landscapes form in rocks rich in ______.

Answer 94

Soluble carbonate (limestone, dolostone).

Question 95

Groundwater discharge where water table intersects land surface.

Answer 95

Spring.

Question 96

What fraction of Earth’s unfrozen freshwater is groundwater?

Answer 96

≈ 30 % (vs. ~1 % surface water, 69 % ice).

Question 97

Valley shaped by glacial erosion has a ______ cross‑section.

Answer 97

U‑shaped.

Question 98

Line separating accumulation and ablation zones on a glacier.

Answer 98

Equilibrium line (snowline).

Question 99

What is till?

Answer 99

Unsorted sediment deposited directly by glacier ice.

Question 100

Desert pavement forms by ______ removing fine particles.

Answer 100

Deflation (wind erosion).

Question 101

Name the wind‑blown sediment deposit that blankets large areas in China and the U.S. Midwest.

Answer 101

Loess.

Question 102

Star dunes form where wind direction is ______.

Answer 102

Variable/multidirectional.

Question 103

During glacial maximum, global sea level was about ______ meters lower than today.

Answer 103

~120 m.

Question 104

Process by which desertification expands along the Sahel region of Africa.

Answer 104

Overgrazing, deforestation, climate change reduce vegetation, exposing soil to erosion.