Why This Matters
Understanding major landforms is essential because they're the foundation of physical geography—literally shaping where people live, how climates behave, and why ecosystems develop the way they do. You're being tested on your ability to explain formation processes, erosional versus depositional origins, and the connections between landforms and human activity. The exam loves asking why a landform exists in a particular location and how it influences everything from agriculture to settlement patterns.
Don't just memorize a list of landform names. Instead, focus on what forces created each landform (tectonic activity, erosion, deposition, glaciation) and how that landform interacts with climate, ecosystems, and human populations. When you can explain the "why" behind a landform, you can tackle any FRQ or multiple-choice question they throw at you.
These landforms result from forces deep within the Earth—plate convergence, divergence, and volcanic activity. They represent the constructive side of geomorphology, where new terrain is built up rather than worn down.
Mountains
- Formed by tectonic plate convergence or volcanic activity—when plates collide, crust crumples upward creating fold mountains like the Himalayas
- Act as orographic barriers that force air masses to rise, cool, and release precipitation on windward slopes while creating rain shadows on leeward sides
- Support altitudinal zonation—distinct ecosystem bands from base to summit due to temperature and moisture gradients
Volcanoes
- Openings in Earth's crust where magma, ash, and gases escape—found at divergent boundaries, convergent boundaries, and hotspots
- Create highly fertile soils through weathering of volcanic ash and lava, supporting intensive agriculture in places like Indonesia and Hawaii
- Classified by eruption style—shield volcanoes (gentle slopes, fluid lava) versus stratovolcanoes (steep, explosive, dangerous)
Rift Valleys
- Formed by tectonic plate divergence—as plates pull apart, the land between them drops, creating elongated depressions
- The East African Rift is the classic example, featuring lakes (Tanganyika, Malawi) and active volcanism along its length
- Often mark early stages of continental breakup—millions of years from now, the East African Rift may become an ocean basin
Compare: Mountains vs. Rift Valleys—both result from tectonic forces, but mountains form from compression while rift valleys form from extension. If an FRQ asks about plate tectonics and landforms, these two illustrate opposite processes perfectly.
These features form when rock and sediment are worn away by water, ice, wind, or gravity. The key is identifying which erosional agent shaped the landform.
Valleys
- Shaped by the erosional agent that carved them—V-shaped valleys indicate river erosion, while U-shaped valleys reveal glacial origins
- Rivers cut downward through hydraulic action and abrasion, while glaciers scour wide, flat-bottomed troughs
- Often serve as natural transportation corridors and settlement sites due to flat floors and water access
Canyons
- Deep, narrow valleys with steep walls formed primarily by river downcutting through rock over millions of years
- Expose geological history—layered rock walls reveal stratigraphic sequences, with oldest rocks at the bottom
- The Grand Canyon exemplifies how a relatively small river (the Colorado) can carve massive features given enough time and uplift
Fjords
- Glacially carved valleys flooded by seawater—formed when glaciers eroded below sea level, then melted and allowed ocean water to enter
- Characterized by extreme depth and steep cliff walls—Norway's Sognefjord reaches over 1,300 meters deep
- Found only in formerly glaciated coastal regions—Norway, Chile, New Zealand, Alaska, and western Canada
Compare: Canyons vs. Fjords—both are deep, dramatic erosional features, but canyons are carved by rivers in arid/semi-arid regions while fjords are carved by glaciers and filled with seawater. Shape is your clue: V-profile suggests river, U-profile suggests glacier.
Mesas and Buttes
- Flat-topped remnants of resistant rock left standing after softer surrounding material eroded away
- Mesas are wider than they are tall; buttes are taller than they are wide—buttes represent a more advanced stage of erosion
- Common in arid regions like the American Southwest, where differential erosion of horizontal rock layers is clearly visible
When erosional agents lose energy, they drop their sediment load, building new landforms through accumulation. These features are constructive but through external processes rather than tectonic forces.
Plains
- Extensive flat areas formed by sediment deposition—alluvial plains from rivers, glacial till plains from ice sheets, or coastal plains from marine sediments
- Among Earth's most agriculturally productive regions due to deep, fertile soils and gentle topography
- Support high population densities—the Indo-Gangetic Plain, North China Plain, and Great Plains are population and agricultural heartlands
Deltas
- Fan-shaped deposits at river mouths where flowing water meets standing water and loses velocity, dropping sediment
- Classified by shape—arcuate (Nile), bird's foot (Mississippi), or cuspate (Tiber) depending on wave energy and sediment supply
- Extremely vulnerable to sea level rise and subsidence—major deltas like the Ganges-Brahmaputra support millions but face existential climate threats
- Beaches form from wave deposition of sand and sediment, while cliffs form from wave erosion undercutting rock
- Spits, bars, and barrier islands develop through longshore drift moving sediment parallel to the coast
- Dynamic systems constantly reshaped by storms, tides, and sea level changes—critical for understanding coastal management
Compare: Plains vs. Deltas—both are depositional and agriculturally valuable, but plains form across broad areas over long time periods while deltas form specifically at river mouths. Deltas are more vulnerable to flooding and sea level rise due to their low elevation and coastal position.
Glaciers are powerful erosional and depositional agents, leaving distinctive signatures on landscapes they've occupied. Understanding glacial features helps reconstruct past climates.
Glaciers
- Massive ice bodies that flow under their own weight—classified as alpine (mountain) glaciers or continental ice sheets
- Erode through plucking and abrasion, carving cirques, arêtes, horns, and U-shaped valleys
- Serve as climate indicators—their advance and retreat directly reflects temperature changes, making them critical for climate science
Hills
- Drumlins and moraines are glacially deposited hills—drumlins are streamlined, elongated hills showing ice flow direction; moraines are ridges of debris
- Can also form through erosion of softer rock around resistant cores, or through tectonic folding
- Influence local microclimates by affecting air drainage and creating rain shadow effects at small scales
Compare: Glaciers vs. Rivers as erosional agents—glaciers create U-shaped valleys, cirques, and fjords through powerful scouring, while rivers create V-shaped valleys and canyons through downcutting. Glacial landscapes look "smoothed" and rounded; fluvial landscapes look sharper and more angular.
Elevated Flatlands
These landforms combine high elevation with relatively flat surfaces, creating unique environments distinct from both mountains and lowland plains.
Plateaus
- Elevated flatlands with at least one steep side—formed by volcanic activity (Columbia Plateau), tectonic uplift (Colorado Plateau), or erosion of surrounding areas
- Often contain valuable mineral resources and can support agriculture where precipitation is adequate
- Create rain shadow effects similar to mountains, influencing regional climate patterns
Compare: Plateaus vs. Plains—both are relatively flat, but plateaus sit at higher elevations with steep edges while plains are low-lying. The Tibetan Plateau averages 4,500 meters; the Great Plains average around 500 meters. This elevation difference dramatically affects climate and human use.
These landforms represent specialized environments shaped by extreme aridity or oceanic isolation, each with distinctive formation processes and ecological significance.
Deserts
- Defined by aridity, not temperature—receive less than 250mm of precipitation annually, found in subtropical high-pressure zones, rain shadows, and continental interiors
- Characterized by aeolian (wind) processes—sand dunes, desert pavement, and wind-eroded landforms dominate
- Support specialized xerophytic ecosystems with adaptations like deep roots, water storage, and nocturnal activity patterns
Islands
- Formed through multiple processes—continental islands (separated from mainlands), oceanic islands (volcanic hotspots or coral atolls), or barrier islands (depositional)
- Exhibit high endemism due to geographic isolation—species evolve independently, creating unique biodiversity (Galápagos, Madagascar)
- Vulnerable to sea level rise and invasive species—isolation that fostered unique ecosystems also limits resilience
Compare: Deserts vs. Islands—both can be considered "isolated" environments (deserts by aridity, islands by water), and both develop specialized endemic species. However, desert isolation is permeable while island isolation is more absolute, leading to even higher endemism rates on islands.
Quick Reference Table
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| Tectonic uplift/convergence | Mountains, Plateaus, Volcanoes |
| Tectonic divergence | Rift Valleys |
| River erosion | V-shaped Valleys, Canyons |
| Glacial erosion | U-shaped Valleys, Fjords, Cirques |
| River deposition | Deltas, Alluvial Plains |
| Glacial deposition | Moraines, Drumlins, Till Plains |
| Wave processes | Beaches, Cliffs, Spits, Barrier Islands |
| Wind processes | Sand Dunes, Desert Pavement |
| Differential erosion | Mesas, Buttes |
| Geographic isolation | Islands (endemism), Deserts (xerophytes) |
Self-Check Questions
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Which two landforms both result from tectonic forces but from opposite processes (compression vs. extension)? Explain the mechanism behind each.
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A geologist finds a valley with steep walls, a flat bottom, and a U-shaped cross-section. What erosional agent created it, and what other landforms would you expect to find nearby?
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Compare and contrast deltas and alluvial plains. How are their formation processes similar, and why are deltas more vulnerable to climate change?
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An FRQ asks you to explain how a single river can create both erosional and depositional landforms. Which landforms would you use as examples, and where along the river's course would each form?
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Why do islands typically have higher rates of endemic species than deserts, even though both environments create ecological isolation? Connect your answer to the concept of geographic barriers.