STRAND A · CHAPTER 02
Earth in Motion
Mountains rise. Continents move. Rock never really sits still.
Earth’s surface is shaped by energy from inside the planet and forces acting at the surface. Landforms are snapshots in processes that can last seconds or millions of years.
CHAPTER 2
Lesson Six: Earth’s Major Landforms
Read the shape of the land
Mountains, plateaus, plains, valleys, and shields are not random bumps. Their shapes and locations record the processes that built and changed them.
Mountains have high relief and steep slopes. Fold mountains form where crust is compressed; volcanic mountains build from erupted material; fault-block mountains rise when large crustal blocks move. A plateau is elevated land with a broad surface. A plain is low-relief land that may form from sediment, glacial deposits, or old erosion surfaces.
Valleys are long low areas, often shaped by rivers or glaciers. River valleys commonly have V-shaped profiles; glacial valleys are often wider and U-shaped. A shield is a large area of ancient exposed or shallowly covered rock. The Canadian Shield contains some of Earth’s oldest rocks.
Landforms create opportunities and challenges. Plains can support farming and transportation; mountains can provide water, minerals, hydroelectric sites, and tourism but make construction difficult. A landform matters because of its relationships with climate, water, soil, vegetation, and people.
Names are useful, but real landscapes overlap categories. A mountain region contains valleys and plateaus; a plain may be crossed by river bluffs. Geographers classify to see patterns, not to pretend nature fits perfect boxes.
Global shaded relief. Long mountain belts, broad plains, plateaus, and ocean basins form visible global patterns.
Classify landforms with more than one clue
Landform names describe patterns of elevation, relief, slope, shape, rock, and origin. A mountain usually has high relief and steep slopes. A plateau stands high but may have a broad, fairly level surface. A plain has low relief, although it may sit well above sea level.
Classification is useful because it helps geographers compare landscapes, but real places overlap. A mountain region contains valleys, ridges, basins, and small plains. The strongest identification uses several clues and explains the process that built or reshaped the land.
Mountains can look similar and have different origins
Fold mountains develop where compression bends and thickens layers of rock. Fault-block mountains form where large crustal blocks move along faults, leaving raised ranges and lowered basins. Volcanic mountains grow as lava, ash, and other erupted material collect around vents.
The shape alone does not always reveal the whole story. Erosion can round an old folded range, while a young fault scarp may look sharp. Geologists combine landform shape with rock layers, faults, volcanic deposits, ages, and regional tectonic patterns.
The diagram is a simplified model; the photographs show more complicated real landscapes. Notice how geographers connect visible form to rock structure and process instead of memorizing one perfect mountain shape.
Rivers and glaciers leave different valley evidence
A river concentrates erosion in a narrow channel and usually cuts downward, producing a V-shaped cross-section. A glacier fills much more of a valley. Moving ice scrapes and plucks the floor and sides, often widening and deepening an older river valley into a broad U shape.
The letters V and U are useful models, not perfect rules. Landslides, rock type, tributaries, and later erosion can change the profile. Students should look for several clues: valley width, floor shape, wall steepness, deposits, and the process that could produce them.
Compare the broad floors and steep sides. Glaciers often follow earlier river valleys, then enlarge them. This explains why a river may flow today through a valley whose overall shape was created mainly by ice.
Landforms shape opportunities, limits, and settlement
Plains often support farming, roads, and large settlements because low relief makes movement and construction easier. Mountains can supply water, minerals, tourism, and hydroelectric sites, but steep slopes raise building costs and increase rockfall, avalanche, and landslide risk.
The Canadian Shield is not one mountain range. It is a huge region of ancient crystalline rock, thin soils, and many lakes, much of it reshaped by glaciers. Its geology supports mining and hydroelectric development, while thin soils and exposed rock make large-scale agriculture difficult in many areas.
The Shield forms a vast curved region around Hudson Bay rather than a single narrow range. The map helps explain mineral and landform patterns, but it does not show soil depth, present land use, community rights, or economic decisions by itself.
GEOGRAPHY WORDS
a natural feature of Earth’s surface
difference between the highest and lowest elevation
a broad area of relatively low relief
an ancient region of exposed or thinly covered crystalline rock
the height of a place above a reference level
a broad elevated landform with a relatively level surface
a mountain region formed mainly by compression and folding of crust
a mountain formed when crustal blocks move along faults
a broad valley commonly widened and deepened by glacial ice
GEOGRAPHIC INVESTIGATION
Read the landform pattern.
- Find one long mountain belt.
- Find one broad low-relief region.
- Compare the pattern with a plate-boundary map.
- Predict one opportunity and one challenge in each.
Reveal the geographic reasoning
Mountain belts often follow plate boundaries, while plains frequently occupy sedimentary basins or areas reshaped by ice and rivers.
YOUR TURN
Which comparison is most accurate?
STUDY + APPLY
Questions that rebuild the whole lesson
Answer from memory first. Open the explanation only after you have committed to an idea.
01COMPARISONHow can a plateau and a plain both have low relief but still be different?
Both may be fairly flat, but a plateau stands at a higher elevation above surrounding land.
02PROCESSWhat evidence helps distinguish fold mountains from fault-block mountains?
Folded rock layers suggest compression, while large faults and raised or lowered blocks support fault-block movement.
03VISUAL EVIDENCEWhich visible features help identify a glacial U-shaped valley?
A broad floor, steep sides, and a valley much wider than the present stream are useful clues.
04MISCONCEPTIONWhy is the Canadian Shield not one mountain range?
It is a vast ancient bedrock region containing many landforms, lakes, and areas of exposed or thinly covered rock.
05INTERRELATIONSHIPGive one opportunity and one challenge created by mountain terrain.
Possible opportunities include water, hydropower, mining, and tourism. Challenges include steep transport routes, construction costs, landslides, rockfall, or avalanches.
06SYNTHESISWhy should a landform be identified with several clues rather than one memorized picture?
Real landscapes overlap and change. Elevation, relief, slope, shape, rock, and process together support a more defensible classification.
CHAPTER 2
Lesson Seven: Inside the Earth
A thin crust above a restless planet
The solid ground under your feet is the outer skin of a planet hot enough inside to deform rock and drive slow movement.
Earth has layers defined by composition and behaviour. The crust is thin and rocky. The mantle is mostly solid rock that can flow extremely slowly over long time scales. The outer core is liquid iron and nickel. The inner core is solid because enormous pressure overcomes the high temperature.
The lithosphere includes the crust and rigid uppermost mantle. It is broken into tectonic plates. Below it, part of the upper mantle behaves more plastically, allowing plates to move centimetres per year.
Earth’s internal heat comes partly from its formation and partly from radioactive decay. Heat moves through the mantle, while gravity helps pull dense oceanic plates downward. Scientists debate the exact balance of forces, but plate motion is measured directly with GPS.
We cannot drill through the mantle. Scientists infer Earth’s interior from seismic waves, gravity, magnetism, high-pressure experiments, and meteorites. A model is strong when different evidence points to the same structure.
Earth cutaway. The crust is extremely thin compared with the mantle and core; the cutaway makes the hidden layers visible but is not a photograph of Earth’s interior.
READ THE CUTAWAY
Outside to centre
The thin outer skin. Oceanic crust is generally thinner than continental crust.
The thickest layer. Slow movement here is connected to plate motion.
Its moving metal helps generate Earth’s magnetic field. S-waves do not pass through it.
It stays solid because pressure at Earth’s centre is enormous.
Earth can be divided by composition or behaviour
The crust, mantle, outer core, and inner core describe what Earth’s major layers are made of. The crust is rocky and thin. The mantle is mostly solid silicate rock. The core is rich in iron and nickel, with a liquid outer part and solid inner part.
A second model describes how materials behave. The lithosphere is the rigid crust plus the uppermost mantle. It is broken into plates. Beneath it, the asthenosphere is a hotter, weaker part of the upper mantle that can deform slowly. These boundaries differ because the two models answer different questions.
The diagram reveals layers that cannot be photographed directly. Notice how thin the crust is beside the mantle. Colours are symbolic and some thin layers are enlarged so they can be seen.
The mantle is mostly solid rock
The mantle is not a global ocean of liquid magma. Most mantle rock is solid. However, high temperature and pressure allow parts of it to deform extremely slowly over millions of years. A material can act rigidly during a short event and still flow over a very long time.
The inner core is solid even though it is hotter than the outer core because pressure is much greater at Earth’s centre. Temperature alone does not decide whether matter is solid or liquid. Pressure and composition also matter.
The wedge compares layer thicknesses more honestly than many colourful classroom cutaways. The crust is only a thin outer skin beside the roughly 2,900-kilometre mantle. The model is still simplified and not a photograph.
Seismic waves reveal hidden layers
Scientists cannot drill through the mantle, so they study how earthquake waves travel. P-waves can pass through solids and liquids, although their speed and direction change. S-waves move only through solids. Seismographs around the world record where each type arrives or disappears.
The absence of direct S-waves beyond the outer core creates a shadow zone, supporting the conclusion that the outer core is liquid. Other changes in wave speed reveal boundaries between materials. The evidence is indirect, but it is repeatable and can be tested with earthquakes from many locations.
Trace the paths from the earthquake through Earth. P-waves bend and cross the core, while direct S-waves stop at the liquid outer core. The pattern recorded by many stations supports a layered interior.
Internal heat and gravity help move plates
Earth’s interior still contains heat left from the planet’s formation, and radioactive decay continues to produce heat. Heat moves through the mantle. Gravity also matters: cold, dense oceanic lithosphere can sink at subduction zones and help pull a plate.
Scientists do not rely on one simple ‘conveyor belt’ picture. Plate motion comes from interacting forces, and GPS now measures movement directly at centimetres per year. Over millions of years, those tiny annual changes can open oceans, build mountains, and shift entire continents.
Earthquakes and volcanoes form long belts near many plate boundaries. Their pattern is surface evidence that the rigid lithosphere is broken and moving. The map shows location and association, while GPS and geology are needed to measure and explain motion.
GEOGRAPHY WORDS
Earth’s thin outer rock layer
the thick layer of hot rock below the crust
Earth’s iron-rich centre
the rigid crust and uppermost mantle broken into plates
the liquid iron-rich layer surrounding the inner core
the solid iron-rich centre of Earth
a weaker, slowly deforming part of the upper mantle beneath the lithosphere
energy that travels through Earth after an earthquake or controlled source
a conclusion reached from evidence rather than direct observation
GEOGRAPHIC INVESTIGATION
How can scientists know what they cannot see?
- Compare P-wave and S-wave behaviour.
- Identify which waves pass through liquids.
- Connect missing S-waves to the outer core.
- State why this is an inference, not a photograph.
Reveal the geographic reasoning
S-waves do not travel through the liquid outer core. Their shadow zone is evidence for a layered interior.
YOUR TURN
Why is Earth’s inner core solid while the outer core is liquid?
STUDY + APPLY
Questions that rebuild the whole lesson
Answer from memory first. Open the explanation only after you have committed to an idea.
01MODELSHow is the crust–mantle–core model different from the lithosphere–asthenosphere model?
The first groups layers by composition. The second groups parts of the outer Earth by mechanical behaviour.
02MISCONCEPTIONWhy is it inaccurate to say tectonic plates float on an ocean of liquid magma?
Most mantle rock is solid. Plates are rigid lithosphere moving above weaker solid mantle that can deform slowly.
03EVIDENCEHow do S-waves support the conclusion that the outer core is liquid?
S-waves do not travel through liquids, and their shadow zone begins where paths would have crossed the outer core.
04CAUSEWhy is the inner core solid even though it is extremely hot?
Enormous pressure at Earth’s centre keeps it solid.
05SCALEWhy do diagrams often exaggerate the crust’s thickness?
The crust is so thin compared with the mantle and core that it would be difficult to see at true scale.
06SYNTHESISExplain why Earth’s interior model is scientific even though humans cannot visit most layers.
Several independent measurements, especially seismic waves, gravity, magnetism, experiments, and meteorites, produce testable conclusions that agree with one another.
CHAPTER 2
Lesson Eight: Plate Tectonics
The map of hazards is also a map of moving plates
Tectonic plates move only centimetres per year, but across millions of years they open oceans, close seas, build mountains, and rearrange continents.
At divergent boundaries, plates move apart and new crust forms, as along the Mid-Atlantic Ridge. At convergent boundaries, plates collide. Dense oceanic lithosphere can sink beneath another plate in subduction, producing trenches, volcanoes, and earthquakes. Continental collision can crumple crust into enormous mountain ranges.
At transform boundaries, plates slide past each other. Crust is neither created nor destroyed, but friction can lock faults until stored strain is released as an earthquake. The San Andreas Fault is a famous example.
The Himalaya formed as India collided with Eurasia. The Andes rise where the Nazca Plate subducts beneath South America. Iceland sits on the Mid-Atlantic Ridge, where plate separation and a mantle hotspot combine. One theory explains patterns on several continents.
Evidence includes matching fossils and rocks across oceans, the fit of continental margins, magnetic stripes on the seafloor, the age pattern of ocean crust, and direct GPS measurements. Plate tectonics succeeded because it connected many clues.
Major tectonic plates and boundary types. Compare this with global earthquake and volcano maps: the spatial match is not accidental.
Wegener recognized a pattern before he had a mechanism
In 1912, Alfred Wegener argued that continents had once been joined and later drifted apart. The fit of continental margins was only one clue. Matching fossils, related rock and mountain belts, and evidence of ancient climates also formed patterns across oceans.
Many scientists rejected continental drift because Wegener could not explain a force strong enough to move continents through ocean crust. Ridicule was unfair, but the scientific objection about mechanism was serious. A strong explanation needs both evidence that movement happened and a workable process that can produce it.
A coastline match by itself could be coincidence or visual selection. Fossils, rock belts, and past-climate evidence add independent lines of support. Several clues pointing in the same direction make the argument stronger.
The ocean floor supplied the missing evidence
During the 1950s, Marie Tharp transformed ship-based depth measurements into profiles and maps of the Atlantic seafloor. She identified a long rift valley running through the Mid-Atlantic Ridge. When earthquake locations lined up with the rift, an independent dataset supported the same active pattern.
Later evidence included the ages of ocean crust and symmetrical magnetic stripes on both sides of mid-ocean ridges. New crust forms near a ridge, records Earth’s magnetic polarity as it cools, and moves outward. Mirror-image stripes showed seafloor spreading and supplied a mechanism for continental movement.
The seafloor map shows the long ridge and rift pattern. The magnetic diagram explains how new crust records repeated polarity changes. Together they connect a mapped feature to a moving process.
Boundary type predicts process and landform
At divergent boundaries, plates move apart and new crust forms at many mid-ocean ridges. At ocean–continent convergent boundaries, dense oceanic lithosphere sinks in subduction, helping produce trenches, earthquakes, and volcanic arcs. When two continents collide, neither sinks easily, so crust thickens and folds into large mountain systems.
At transform boundaries, plates slide sideways. Crust is not created or destroyed, but faults may lock and store strain until an earthquake releases it. Boundary labels are useful because they connect motion to process, landform, and likely hazard.
Earthquakes and volcanoes cluster in long belts rather than appearing randomly. Many belts follow plate boundaries. The overlap is strongest at subduction zones, while transform earthquakes and hotspot volcanoes create important exceptions.
Use real landscapes to test the model
The Andes form where the Nazca Plate subducts beneath South America. The Himalaya developed through collision between India and Eurasia. The San Andreas Fault marks sideways transform motion in California. Iceland lies on the Mid-Atlantic Ridge and above a mantle hotspot, so more than one factor shapes its volcanism.
Plate tectonics became powerful because it explained many observations with one connected theory: continent movement, seafloor age, magnetic stripes, mountain belts, trenches, earthquakes, and volcanoes. GPS now directly measures plate motion. Extraordinary claims became accepted when extraordinary evidence accumulated.
The long mountain and volcano belt lies above the subducting Nazca Plate. The photograph shows the real landscape produced by a much larger tectonic system. A plate map is still needed to identify the boundary beneath it.
GEOGRAPHY WORDS
a moving slab of lithosphere
the sinking of one plate beneath another
a boundary where plates move apart
a boundary where plates slide past one another
the early idea that continents move across Earth’s surface
a long underwater mountain system where new ocean crust forms
the creation and outward movement of ocean crust at a divergent boundary
a boundary where plates move toward one another
convergence in which two buoyant continental masses compress and thicken crust
GEOGRAPHIC INVESTIGATION
Boundary detective
- Find a divergent boundary in the Atlantic.
- Find a subduction zone around the Pacific.
- Locate a continental collision.
- Predict the hazard or landform at each.
Reveal the geographic reasoning
Boundary type helps predict patterns: ridges at divergence, trenches and volcanic arcs at subduction, mountains at collision, and shallow earthquakes at transforms.
YOUR TURN
Which process creates new oceanic crust?
STUDY + APPLY
Questions that rebuild the whole lesson
Answer from memory first. Open the explanation only after you have committed to an idea.
01HISTORY OF SCIENCEWhy was Wegener’s evidence important but not yet enough for broad acceptance?
The patterns suggested movement, but he could not provide a convincing mechanism that could move continents.
02EVIDENCEHow did Marie Tharp’s work strengthen the case for moving plates?
Her seafloor profiles revealed a long ridge and central rift, and earthquake locations lined up with that active feature.
03PROCESSWhat creates new oceanic crust?
Magma rises and cools where plates move apart at many mid-ocean ridges.
04COMPARISONHow is continental collision different from ocean–continent subduction?
Dense oceanic lithosphere can sink beneath a continent, while two buoyant continents mainly compress and thicken the crust.
05MAP INTERPRETATIONWhy do earthquake and volcano belts overlap strongly but not perfectly?
Subduction creates both, but transform boundaries produce earthquakes without volcanic arcs and hotspots can produce volcanoes away from boundaries.
06SYNTHESISWhy is plate tectonics considered a strong scientific theory?
It connects many independent observations and processes, makes predictions about landforms and hazards, and is supported by direct GPS measurements.
CHAPTER 2
Lesson Nine: Earthquakes and Volcanoes
Hazard is not the same as disaster
An earthquake is a sudden release of stored energy in rock. A volcano is an opening through which magma, gas, and ash reach the surface. Their impacts depend on both physical power and human vulnerability.
An earthquake begins at the focus; the epicentre is the point directly above it on the surface. Magnitude measures energy released. Intensity describes observed shaking and damage in a particular place. Distance, depth, ground conditions, and building design all affect intensity.
Volcanoes differ. Runny basaltic magma can produce broad shield volcanoes. Stickier, gas-rich magma can build steep composite volcanoes and explosive eruptions. Hazards include lava, ash, toxic gases, fast pyroclastic flows, and mudflows called lahars.
A hazard becomes a disaster when it strikes exposed, vulnerable communities. Strong building codes, warning systems, public education, and evacuation routes can reduce losses. Poverty, weak infrastructure, and unstable slopes can increase them.
The 2011 Tōhoku earthquake generated a devastating tsunami in Japan. The event showed both the value and limits of preparedness: advanced engineering saved lives, yet the scale overwhelmed defences and triggered the Fukushima nuclear disaster.
Kīlauea, Hawaiʻi. Lava is the visible part of a larger volcanic system; the danger depends on eruption style, location, warning time, exposure, and evacuation.
Earthquakes begin below the surface
Stress builds as rocks on opposite sides of a fault remain locked while plates keep moving. When friction is overcome, the fault slips and stored energy travels outward as seismic waves. The focus is the underground starting point; the epicentre is the surface location directly above it.
Magnitude describes the energy released by the earthquake. Intensity describes shaking and damage at a particular place. One earthquake has one reported magnitude but many intensities because distance, depth, ground material, building design, and local conditions vary.
The dense earthquake symbols form long belts around the Pacific, through the Mediterranean–Himalayan region, and along mid-ocean ridges. The map shows a global pattern, not exact local risk for every community.
Volcano shape and hazard depend on magma and setting
Hot, runny basaltic magma can spread in long lava flows and build broad shield volcanoes. Cooler, stickier, gas-rich magma can trap pressure and produce explosive eruptions, building steep composite volcanoes from alternating lava and broken material.
Lava is only one volcanic hazard. Ash can damage lungs, machinery, roofs, crops, and aircraft far downwind. Pyroclastic flows race down slopes as hot mixtures of gas, ash, and rock. Lahars carry water and volcanic debris along valleys, sometimes long after an eruption. Gas can threaten areas even without spectacular lava.
The images show why ‘volcano danger’ is not one thing. Each hazard has a different speed, path, and reach. Risk planning must therefore use local valleys, wind, population, monitoring, and evacuation evidence.
Hazard does not automatically equal disaster
A hazard is a potentially damaging physical event or process. Exposure describes the people, buildings, and systems located in harm’s way. Vulnerability describes conditions that make them more likely to be harmed. Disaster risk rises when a strong hazard meets high exposure and vulnerability.
Preparedness can reduce vulnerability without changing the earthquake or volcano. Building codes, land-use rules, monitoring, public education, evacuation routes, and reliable communication can save lives. Poverty, weak infrastructure, unstable slopes, crowded settlements, and limited emergency capacity can increase losses.
Tōhoku shows a cascading disaster
On 11 March 2011, a magnitude 9.1 megathrust earthquake occurred off northeastern Japan. Sudden seafloor movement displaced a huge volume of water and generated a tsunami. As the waves entered shallow coastal water, they slowed and grew taller, flooding low coastal plains and travelling far inland.
Japan’s preparation saved lives, but the event exceeded many defences. Floodwater damaged communities and cut power at the Fukushima Daiichi nuclear plant. Backup generators were flooded, cooling systems failed, and reactor cores melted. The chain shows how physical hazards, geography, infrastructure, and human decisions combine.
The satellite image reveals the physical extent of flooding but not the full human experience. The plant photograph identifies critical infrastructure but does not explain the failure chain by itself. The historical explanation requires both evidence and chronology.
GEOGRAPHY WORDS
the underground point where an earthquake begins
the surface point directly above the focus
a measure of energy released by an earthquake
conditions that make people or systems more likely to be harmed
the strength of shaking and effects observed at a particular location
people, buildings, infrastructure, and activities located where a hazard may strike
a fast, hot flow of volcanic gas, ash, and rock
a rapidly moving mixture of water and volcanic debris
a series of long waves produced by sudden displacement of water
GEOGRAPHIC INVESTIGATION
Compare hazard and vulnerability.
- Identify the physical hazard.
- Map who and what was exposed.
- List conditions that reduced risk.
- List conditions that increased risk.
Reveal the geographic reasoning
The strongest event does not automatically cause the worst disaster. Population, construction, wealth, governance, and geography change outcomes.
YOUR TURN
Which statement best explains why equal-magnitude earthquakes can have very different impacts?
STUDY + APPLY
Questions that rebuild the whole lesson
Answer from memory first. Open the explanation only after you have committed to an idea.
01UNDERSTANDINGHow are an earthquake’s focus and epicentre different?
The focus is the underground starting point. The epicentre is the point on the surface directly above it.
02COMPARISONHow are magnitude and intensity different?
Magnitude measures the event’s released energy. Intensity describes shaking and damage at a specific place.
03VOLCANOESWhy can sticky, gas-rich magma produce a more explosive eruption?
It traps gas pressure more easily than runny magma, allowing pressure to build before release.
04VISUAL EVIDENCEWhy are lahars dangerous far from a volcanic crater?
They follow valleys and drainage routes, carrying water and debris rapidly into distant communities.
05CASE STUDYTrace the Tōhoku disaster from plate movement to the Fukushima crisis.
Fault slip displaced the seafloor, generating a tsunami; coastal flooding reached infrastructure, flooded backup power, stopped cooling, and contributed to core melts.
06SYNTHESISWhy can two earthquakes of similar magnitude produce very different disasters?
Depth, distance, ground conditions, exposure, building strength, poverty, preparedness, and emergency capacity can all differ.
CHAPTER 2
Lesson Ten: Weathering, Erosion and Changing Landforms
Break it. Move it. Drop it.
Weathering breaks rock down. Erosion moves the material. Deposition drops it somewhere else. Mix those up and the whole landscape story falls apart.
Mechanical weathering breaks rock without changing its minerals. Water freezing in cracks, roots growing, salt crystals expanding, and heating and cooling can all weaken rock. Chemical weathering changes minerals through reactions with water, oxygen, or acids.
Gravity, rivers, waves, wind, and glaciers erode and transport sediment. Energy controls what can move: fast water carries larger material; slower water drops it. Deposition builds floodplains, deltas, beaches, dunes, and glacial landforms.
Glaciers scrape and pluck rock, carve U-shaped valleys, and carry debris. When ice melts, it deposits mixed sediment as till. Much of Canada’s soil, lake pattern, and surface shape reflects repeated glaciation.
Humans speed or redirect these processes. Removing vegetation can increase runoff and soil erosion. Dams trap sediment. Roads cut slopes. Shore protection may save one property while shifting erosion farther down the coast.
Weathering breaks rock in place. Erosion moves the loosened material. Deposition occurs where energy drops and sediment settles.
FOLLOW THE MATERIAL
The words describe different moments.
Rock becomes smaller pieces without travelling away yet.
Water, wind, ice, or gravity carries the material.
The mover loses energy, so sediment settles.
A river slows when it enters a lake. Which process should increase?
Deposition. Slower water has less energy to carry sediment, so more material settles to the bottom.
Diagnose the process by what the material is doing
Weathering changes rock where it is. Erosion removes and transports material. Deposition occurs when the transporting system loses enough energy for particles to settle. The same grain can move through all three processes at different times, so the correct word depends on its behaviour at that moment.
Mechanical weathering changes the size or shape of rock without changing its minerals. Freeze–thaw, growing roots, salt crystals, and heating and cooling can widen cracks. Chemical weathering changes minerals through reactions with water, oxygen, or acids. Both kinds often work together.
The angular fragments show rock breaking close to its source. Because the pieces have not travelled far, they remain sharp rather than rounded. The photograph supports weathering and gravity, but not the exact rate or single cause without more evidence.
Moving agents have different energy and reach
Water, wind, ice, and gravity can transport sediment. Fast water can carry larger particles than slow water. Wind usually moves finer material or sand unless storms are very strong. Glaciers can transport a mixed load from clay-sized particles to huge boulders. Gravity moves material downhill in rockfalls, landslides, and soil creep.
Particle shape and sorting preserve clues. Long transport in rivers or waves often rounds particles. Repeated water or wind movement can sort sediment by size. Glacial till is commonly unsorted because melting ice drops many sizes together. These are useful patterns, not perfect rules for every deposit.
Deposition builds land when energy falls
A river deposits its largest particles first when it slows, while finer sediment may travel farther. Repeated floods can build floodplains. A river entering a lake or ocean may spread sediment into a delta. Waves move and deposit sand along beaches, while wind builds dunes and ice leaves ridges of debris called moraines.
Deposition is not simply ‘erosion stopping.’ It is a new process that builds landforms from transported material. A beach can gain sand in one season and lose it in another. A delta grows only when sediment supply is greater than the amount removed by waves, currents, sinking land, or rising water.
The landforms differ because water, waves, wind, and ice move sediment in different ways. Look at location, particle size, sorting, shape, and nearby processes before deciding which agent built a deposit.
Ice reshaped Canada, and people still redirect the system
Glaciers cover, flow, scrape, and pluck. They can widen river-cut valleys, smooth and scratch bedrock, move enormous loads, and leave till when they melt. Repeated glaciation strongly influenced Canada’s soils, lakes, drainage patterns, exposed Shield rock, and broad U-shaped valleys.
Human choices can speed or redirect surface processes. Removing vegetation exposes soil and increases runoff. Roads and quarries cut slopes. Dams trap sediment that would otherwise move downstream. Shore protection may reduce erosion at one property while changing currents and sediment supply farther along the coast.
The sequence model shows change through time, while the real valley shows the visible result. The clear-cut landscape reminds us that present land use can change how quickly water and sediment move across an already glaciated surface.
GEOGRAPHY WORDS
the breakdown of rock in place
the removal and transport of material
the settling of transported material
loose particles of rock, mineral, or organic material
physical breakdown of rock without changing its mineral composition
change to rock minerals through chemical reactions
the movement of sediment by water, wind, ice, or gravity
mixed, usually unsorted sediment deposited directly by glacial ice
a landform built from debris deposited by a glacier
GEOGRAPHIC INVESTIGATION
Follow one grain of sand.
- Choose where the grain is weathered from rock.
- Identify the force that moves it.
- Predict where energy decreases.
- Name the depositional landform that could form.
Reveal the geographic reasoning
A grain can move from mountain to river to floodplain to delta to ocean—and may be buried, cemented, uplifted, and weathered again.
YOUR TURN
A river slows as it enters a lake and drops sand. Which process is occurring?
STUDY + APPLY
Questions that rebuild the whole lesson
Answer from memory first. Open the explanation only after you have committed to an idea.
01DIAGNOSISA root widens a crack in bedrock. Which process is occurring?
Mechanical weathering, because the rock is breaking in place without its minerals being changed.
02ENERGYWhy does a river often deposit gravel before fine silt when it slows?
Gravel requires more energy to transport, so it settles first as the river loses energy.
03COMPARISONHow are erosion and deposition connected but different?
Erosion transports material away. Deposition settles transported material where energy drops, often building a new landform.
04VISUAL EVIDENCEWhat clues might show that a deposit was left by glacial ice?
A mixed, unsorted range of particle sizes, striated rock, moraines, and a nearby glacial landscape are useful clues.
05HUMAN IMPACTHow can a dam reduce one problem and create another downstream?
It can control flow or store water, but it traps sediment and may increase erosion or reduce habitat and delta growth downstream.
06SYNTHESISFollow one grain of sand from bedrock to a delta using the three main process words.
Weathering breaks it from bedrock, erosion transports it by water, and deposition settles it when the river loses energy at the lake or ocean.
PULL IT TOGETHER
Rebuild Chapter 2
01Landform diagnosisHow can the same mountain region be both opportunity and challenge?
How can the same mountain region be both opportunity and challenge?
It may provide water, minerals, tourism, and hydropower while increasing transport cost, slope hazards, and construction difficulty.
02Evidence underfootHow do scientists know plates move?
How do scientists know plates move?
GPS measurements, seafloor ages and magnetic stripes, matching rocks/fossils, and global hazard patterns.
03Hazard equationWhy is magnitude alone not enough to predict disaster?
Why is magnitude alone not enough to predict disaster?
Exposure, vulnerability, depth, ground conditions, and preparedness change impacts.
04Process correctionCorrect: ‘Erosion breaks rock into pieces.’
Correct: ‘Erosion breaks rock into pieces.’
Weathering breaks rock in place; erosion transports the pieces.
ORDER THE SYSTEM
Put the chapter chain in a logical order.
Use cause, process, and consequence—not memorized dates.
CHAPTER SELF-CHECK
Ten questions. Whole chapter.
QUICK REVIEW
You should now be able to…
✓ identify and compare major landforms
✓ describe Earth’s internal layers
✓ explain divergent, convergent, and transform boundaries
✓ connect plate patterns to hazards
✓ distinguish hazard from vulnerability
✓ separate weathering, erosion, and deposition
CHAPTER SOURCES