Rocks, Landscapes & Water — Chapter Practice, Grade 9

Identify Earth materials and explain how rock, water, and surface processes shape landscapes.

Problem 1

Which of these is NOT one of the five traits required for a substance to be classified as a mineral?
  1. Naturally occurring
  2. Made of living tissue
  3. A solid
  4. Definite chemical composition
Answer and explanation

Made of living tissue

Minerals must be inorganic — not created by living organisms; the other three are indeed required traits.

Problem 2

Which property is generally the LEAST reliable for identifying a mineral?
  1. Streak
  2. Color
  3. Hardness
  4. Luster
Answer and explanation

Color

Color is unreliable because trace impurities can cause the same mineral to appear in several different colors.

Problem 3

A mineral breaks apart along smooth, flat surfaces that follow its internal crystal structure. This property is called…
  1. fracture
  2. cleavage
  3. luster
  4. streak
Answer and explanation

cleavage

Breaking along smooth, flat planes that follow the crystal structure is cleavage; uneven, rough breakage is called fracture.

Problem 4

Diamond has a Mohs hardness of 10 and talc has a Mohs hardness of 1. How many whole steps higher is diamond's hardness than talc's?
Answer and explanation

9

10 − 1 = 9.

Problem 5

A student says two minerals must be different because one sample is purple and the other is white. Explain why color alone is not enough evidence, and describe a better test.
Answer and explanation

Many minerals occur in several colors because of trace impurities — for example, quartz can be purple (amethyst), pink (rose quartz), or clear — so two different-colored samples could still be the same mineral. A better test is to compare streak (the color of the powdered mineral) or hardness, which don't change with impurities the way color does.

Problem 6

Sample A scratches calcite (3) but is scratched by fluorite (4). What does this support? Explain the reasoning in your own words.
Answer and explanation

Its Mohs hardness lies between 3 and 4 under this test; other properties are needed for identification.

Scratch resistance exceeds calcite's but is below fluorite's.

Use the ranking as a bracket, not as an exact numerical average.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 7

Two minerals share a color. Give two stronger comparison tests. Show the reasoning, not just the conclusion.
Hints

Hardness is scratch resistance, not how easily a sample breaks.

Answer and explanation

Streak, hardness, cleavage, density or other characteristic properties can distinguish them; choose two and describe the tests.

Problem 8

Why should a weathered surface be avoided in a streak or hardness comparison?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Weathering products can have different properties from the fresh mineral being identified.

Problem 9

A broken face is different from a crystal’s growth faceA broken face is different from a crystal’s growth faceRepeated planar break surfacesIrregular break surfaceCleavage follows structural planes.Fracture has other break geometry.
Original schematic specimen shapes illustrate planar and irregular break geometry. No named mineral is identified by these cartoons. They separate observations of breakage from growth form and do not replace hands-on or photographed specimen evidence.
Interpret the supplied visual model. What observation would distinguish a crystal growth face from evidence of cleavage?
Answer and explanation

Record whether the surface formed during growth or breakage, and look for repeated characteristic planes/angles across breaks. A flat appearance alone is insufficient.

Compare repeated planes on the left with irregular geometry on the right. These are schematic specimen surfaces rather than exact identification photographs.

Record whether the surface formed during growth or breakage, and look for repeated characteristic planes/angles across breaks. A flat appearance alone is insufficient.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 10

A specimen has mass 54 g and displaces water from 20 to 38 mL when fully immersed without bubbles. Find its density and explain what additional evidence is needed to identify its mineral.
Answer and explanation

Volume is 18 mL = 18 cm³, so density is 54/18 = 3 g/cm³. Use hardness, streak, cleavage and other characteristic observations; density alone may match several candidates.

Find displaced volume: 38−20 = 18 cm³.

Calculate density: 54/18 = 3 g/cm³.

Compare several tests and uncertainty rather than naming a mineral from one value.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 11

Which process turns loose sediments into sedimentary rock over time?
  1. Compaction and cementation
  2. Melting and cooling
  3. Heat and pressure deep underground
  4. Weathering into smaller pieces
Answer and explanation

Compaction and cementation

Layers of sediment are pressed together (compaction) and glued by minerals (cementation) to form sedimentary rock.

Problem 12

What is magma called once it erupts above Earth's surface?
  1. Sediment
  2. Lava
  3. Ore
  4. Cement
Answer and explanation

Lava

Magma is called lava once it erupts above the surface.

Problem 13

Which process directly turns loose sediment into solid sedimentary rock?
  1. Metamorphism
  2. Melting
  3. Lithification (compaction and cementation)
  4. Crystallization from magma
Answer and explanation

Lithification (compaction and cementation)

Lithification — compaction plus cementation — squeezes and glues loose sediment into solid sedimentary rock.

Problem 14

Explain why the rock cycle is usually drawn as a loop with arrows going in many directions instead of a single straight line.
Answer and explanation

Because any rock type can change into any other rock type depending on which process acts on it next, there's no fixed starting or ending point, so a loop with many crossing arrows shows all the possible paths.

Problem 15

A geologist finds a rock that used to be metamorphic but is now found surrounded by cooled, hardened lava-like material. Which process most likely happened to the original rock?
  1. It was compacted and cemented
  2. It melted completely into magma, then cooled and crystallized
  3. It was scratched by a harder mineral
  4. It formed layers from deposited sediment
Answer and explanation

It melted completely into magma, then cooled and crystallized

Since the rock is now found within hardened, once-molten material, the original metamorphic rock must have melted into magma before cooling and crystallizing into new igneous rock.

Problem 16

Trace a path from granite to sandstone without melting. Explain the reasoning in your own words.
Answer and explanation

Granite can become sandstone through weathering, transport, deposition and lithification.

Weathering releases grains; erosion transports them and deposition collects them.

Compaction and cementation turn sediment into sedimentary rock.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 17

What process turns loose sediment into sedimentary rock? Show the reasoning, not just the conclusion.
Hints

No melting is specified.

Answer and explanation

Deposition followed by compaction and/or cementation under suitable conditions.

Problem 18

Can an igneous rock become sedimentary without first becoming metamorphic?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Yes. Weathering, erosion, deposition and lithification provide a direct pathway through sediments.

Problem 19

Sand becomes sandstone through burial and grain bindingSand becomes sandstone through burial and grain bindingLoose sedimentBuried and cemented grainsCompaction reduces some pore space; cement binds grains.Deposition alone does not turn every loose deposit into rock.
Original grain-scale models compare loose sediment with a cemented deposit. Cement is shown as a continuous background for visibility, not as a uniform literal mineral in every pore. Grain size and burial load are schematic.
Interpret the supplied visual model. What two processes can distinguish deposited loose sand from lithified sandstone?
Answer and explanation

Compaction can reduce spaces and cementation can bind grains with minerals. Their contribution depends on the deposit; sandstone need not form through one identical sequence or degree of compaction.

Compare loose-grain spaces with the modeled mineral cement around grains. The loading arrow indicates burial stress; it is not an instruction to press sediment by hand.

Compaction can reduce spaces and cementation can bind grains with minerals. Their contribution depends on the deposit; sandstone need not form through one identical sequence or degree of compaction.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 20

A rock contains sand grains cemented together. A student calls cementation the same as cooling molten sand. Distinguish the two pathways and name an observation that could help test the interpretation.
Answer and explanation

Cementation binds deposited grains through mineral precipitation; cooling a melt forms igneous material. Preserved grain boundaries, sedimentary textures and field relationships help test a cemented-sediment interpretation. Melting is not required for sandstone.

Cementation binds deposited grains through mineral precipitation; cooling a melt forms igneous material. Preserved grain boundaries, sedimentary textures and field relationships help test a cemented-sediment interpretation. Melting is not required for sandstone.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 21

A rock cooled quickly at Earth's surface and has tiny crystals you can barely see. What type of rock is this?
  1. Extrusive igneous rock
  2. Intrusive igneous rock
  3. Sedimentary rock
  4. Foliated metamorphic rock
Answer and explanation

Extrusive igneous rock

Fast cooling at the surface produces small or no crystals — that's extrusive (volcanic) igneous rock.

Problem 22

Which rock type forms from melted rock (magma or lava) that cools and hardens?
  1. Igneous
  2. Sedimentary
  3. Metamorphic
  4. Fossil
Answer and explanation

Igneous

Igneous rock forms when molten magma or lava cools and solidifies.

Problem 23

Slate splits along closely spaced, flat surfaces. Slate forms through metamorphism from which original rock?
  1. Granite
  2. Basalt
  3. Shale
  4. Limestone
Answer and explanation

Shale

Slate is a foliated metamorphic rock that forms when shale is subjected to heat and pressure.

Problem 24

Marble (from limestone) and quartzite (from sandstone) both form through metamorphism but show NO banding. What term describes this lack of banding?
  1. Foliated
  2. Non-foliated
  3. Extrusive
  4. Intrusive
Answer and explanation

Non-foliated

Non-foliated rocks lack a pervasive planar fabric. Mineral composition and growth conditions affect whether foliation develops.

Problem 25

A geologist estimates a limestone bed took 50,000 years to accumulate its 100 visible layers. On average, how many years does each layer represent?
Answer and explanation

500 years/layer

50,000 ÷ 100 = 500 years per layer.

Problem 26

Granite and gneiss can form from very similar starting minerals, yet granite has scattered crystals with no pattern while gneiss shows clear banding. Explain why they look so different.
Answer and explanation

Granite is an igneous rock that crystallized directly from slowly cooling magma, so its crystals grew in random orientations. Gneiss is a metamorphic rock formed when intense heat and pressure squeezed an existing rock hard enough to force its minerals to line up in parallel bands, creating foliation, without ever fully melting.

Problem 27

A sample has visible interlocking crystals and no bedding or fossils. Is the evidence enough for a unique rock name? Explain the reasoning in your own words.
Answer and explanation

No; it suggests possibilities but does not uniquely identify the rock.

The texture supports a crystalline origin but can occur in different rocks.

Composition and other features are still needed to distinguish alternatives.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 28

A lava sample cools rapidly and has tiny crystals. Why? Show the reasoning, not just the conclusion.
Hints

Texture supports an inference; composition and context strengthen identification.

Answer and explanation

Rapid cooling allows little time for crystal growth.

Problem 29

A foliated rock has aligned minerals but no evidence of melting. What origin fits?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Metamorphic alteration with differential stress is consistent with foliation; it is not proof of former liquid magma.

Problem 30

Metamorphic rocks can be foliated or nonfoliatedMetamorphic rocks can be foliated or nonfoliatedDirected-stress alignmentRecrystallized, not foliatedFoliation is an alignment/banding pattern; metamorphism can lack it.
Original qualitative metamorphic fabric models. The left isolates alignment under a selected stress geometry; the right illustrates a nonfoliated mosaic. The drawings do not identify exact mineral assemblages or set pressure/temperature values.
Interpret the supplied visual model. Can a rock without foliation still be metamorphic? Explain a suitable mechanism.
Answer and explanation

Yes. It can recrystallize in the solid state without a pronounced aligned fabric, depending on composition and conditions; marble is a common example.

Compare the aligned texture with the grain mosaic. The pressure arrows mark one simplified stress geometry, not complete three-dimensional forces.

Yes. It can recrystallize in the solid state without a pronounced aligned fabric, depending on composition and conditions; marble is a common example.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 31

A specimen has interlocking crystals but no foliation. Is it necessarily igneous? Explain two possible histories and the evidence that would help distinguish them.
Answer and explanation

No. Cooling a melt can yield an igneous crystalline rock, while solid-state recrystallization can yield a nonfoliated metamorphic rock. Mineral composition, texture details, contacts and field relationships help distinguish the histories.

No. Cooling a melt can yield an igneous crystalline rock, while solid-state recrystallization can yield a nonfoliated metamorphic rock. Mineral composition, texture details, contacts and field relationships help distinguish the histories.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 32

Which term describes rock breaking down into smaller pieces WITHOUT being moved from its original location?
  1. Erosion
  2. Deposition
  3. Weathering
  4. Lithification
Answer and explanation

Weathering

Weathering breaks rock down in place; erosion is what moves the pieces away.

Problem 33

Rainwater is naturally slightly acidic and slowly dissolves limestone over many years. This is an example of…
  1. Physical weathering
  2. Chemical weathering
  3. Erosion
  4. Deposition
Answer and explanation

Chemical weathering

Dissolving is a chemical change to the rock's composition, so this is chemical weathering.

Problem 34

Which of these can act as an agent of erosion?
  1. Only earthquakes
  2. Wind, water, ice, and gravity
  3. Only chemical reactions
  4. Only volcanic eruptions
Answer and explanation

Wind, water, ice, and gravity

Erosion transports sediment via wind, water, ice (glaciers), or gravity (mass wasting).

Problem 35

Explain why deposition happens where a fast river meets a calm lake or ocean, rather than somewhere in the middle of the river's fast-flowing course.
Answer and explanation

Deposition happens when a carrying agent loses energy and can no longer hold its sediment load. A fast-flowing river has plenty of energy to keep sediment moving, but when it enters a calm lake or ocean it slows down sharply, loses that energy, and drops its sediment, often building a delta right at the river's mouth.

Problem 36

Much of Westchester County's landscape, including ridges and hills of unsorted rock debris, was shaped mainly by which process during the last Ice Age?
  1. Volcanic eruptions
  2. Glacial erosion and deposition
  3. Chemical weathering from acid rain
  4. Wind erosion in a desert
Answer and explanation

Glacial erosion and deposition

Advancing and retreating glaciers eroded the landscape and deposited moraines and other ridges across the Hudson Valley region during the last Ice Age.

Problem 37

A glacier deposits a moraine ridge that grows by about 2 meters of debris thickness every 100 years it remains in one place. At that rate, how many meters thick would the deposit be after 1,500 years?
Answer and explanation

30 meters

1,500 ÷ 100 = 15 hundred-year periods; 15 × 2 = 30 meters.

Problem 38

A stream slows on entering a lake and deposits gravel near its mouth and finer sediment farther out. Explain. Explain the reasoning in your own words.
Answer and explanation

Deposition and sorting occur as the stream loses energy; size, density and shape influence settling.

Reduced flow speed lowers transport capacity.

Larger grains commonly settle earlier under these conditions.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 39

Water freezes in rock cracks and widens them. Classify the weathering. Show the reasoning, not just the conclusion.
Hints

Identify breakdown, movement and settling separately.

Answer and explanation

Physical weathering by freeze–thaw action, where freezing water expands in suitable conditions.

Problem 40

Why might sediment settle when a river enters a lake?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Flow speed often falls, reducing transport capacity; particle size and density affect settling.

Problem 41

Deposition can occur while water is still movingDeposition can occur while water is still movingFaster channelFlow spreads into a basinReduced carrying conditions can favor deposition.Water can keep moving while material accumulates.
Original channel-to-basin deposition schematic. The deposit is a selected accumulation and its triangular shape is explanatory rather than surveyed geometry. Arrows are qualitative; the diagram does not claim a numeric settling speed or a universal grain-order sequence.
Interpret the supplied visual model. Why could some grains settle while fine material continues farther into the basin?
Answer and explanation

Different grain sizes, densities and shapes have different settling/transport behavior under the changed flow conditions. Depositing one fraction does not stop all water or all material transport.

Trace water into the wider basin and identify the accumulating sediment wedge. Width and arrow lengths indicate a qualitative contrast only.

Different grain sizes, densities and shapes have different settling/transport behavior under the changed flow conditions. Depositing one fraction does not stop all water or all material transport.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 42

Trial A produces 12 g of sediment in 120 mL runoff; trial B 9 g in 60 mL. Compare total sediment export and concentration, then name two conditions to control when testing a surface cover.
Answer and explanation

B exports less mass (9 vs 12 g) but greater concentration (0.15 vs 0.10 g/mL). Control rain input, slope, material and collection interval, except for the planned cover change.

Calculate A: 12/120 = 0.10 g/mL.

Calculate B: 9/60 = 0.15 g/mL.

Distinguish total export from concentration and match test conditions.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Problem 43

Inputs are 120 units and outputs are 100. Find change in storage.
Answer and explanation

20 units

120 − 100 = +20.

Problem 44

High porosity always guarantees high permeability.
  1. True
  2. False
Answer and explanation

False

Pores must be well connected and large enough to transmit water readily.

Problem 45

Why can pumping create a long-term problem in a renewable aquifer?
Answer and explanation

Withdrawals may exceed recharge over the relevant timescale.

Problem 46

A simplified basin receives 120 units of water, loses 85 naturally and has 20 withdrawn. Find storage change. Explain the reasoning in your own words.
Answer and explanation

Storage rises by 15 units in this supplied model, assuming no omitted flows.

Total output=85+20=105 units.

Change=120−105=15 units.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 47

A water store receives 80 units and loses 95 units in a period. Find its change. Show the reasoning, not just the conclusion.
Hints

All quantities must cover the same area and time.

Answer and explanation

80−95=−15 units, a decrease in storage.

Problem 48

How can pumping affect a stream connected to an aquifer?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Lower groundwater levels can reduce groundwater discharge to the stream or induce flow from it, depending on the connection.

Problem 49

Pumping can change the gradient toward a wellPumping can change the gradient toward a wellPumping draws down a local water levelCompare withdrawal, recharge and nearby measured heads.
Original ideal unconfined pumping section. The lowered line represents drawdown in porous material, not an emptied underground bowl. Actual flow and drawdown depend on geological layers, boundaries and time; arrows are not a contaminant-travel prediction.
Interpret the supplied visual model. What records would help distinguish increased pumping from reduced recharge as a cause of declining well levels?
Answer and explanation

Compare pumping volumes/times, rainfall and recharge estimates, water levels in several wells and local geology. A single falling-level series cannot distinguish all causes.

Trace the arrows toward the pumping well and the lowered blue water-table line. The geometry represents an unconfined teaching model.

Compare pumping volumes/times, rainfall and recharge estimates, water levels in several wells and local geology. A single falling-level series cannot distinguish all causes.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 50

A catchment begins with 300 m³ of stored water. Over one month it receives 100 m³ and loses 70 m³ by outflow/evapotranspiration plus 45 m³ by withdrawal. Find storage change and final storage. Explain why high porosity alone would not guarantee fast recharge.
Answer and explanation

Storage change is 100−70−45 = −15 m³ and final storage is 285 m³. Transmission also depends on connected pathways, permeability, gradients and conditions; porosity alone is a storage fraction.

Combine outputs: 70+45 = 115 m³.

Change is −15 m³; add to initial 300 m³ to get 285 m³.

Distinguish pore-space amount from connected transmission.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Browse all courses