- A map shows a dune field at two times: Year 1 (Older) and Year 2 (Newer). In Year 2, several crescent-shaped dunes are in new positions downwind, and a thin layer of sand covers an area that was bare ground in Year 1. Which change is shown, and what process most likely caused it? (More than one process can change deserts.)
Answer: The dunes moved and sand spread because wind eroded and deposited sand over time
The core skill in studying Earth's changing surface is using evidence from maps or images to explain how and why the surface changes over time. Earth's surface is not fixed but changes continuously due to natural processes acting on landforms like desert dunes. Processes such as wind erosion and deposition can shift dunes downwind, moving sand to new locations and covering previously bare areas with thin layers. To check for changes, compare features like dune positions or sand coverage across maps from different time points to track migration patterns. A common misconception is that dunes are permanent and immobile, but they can change positions gradually through wind action rather than being fixed features. Surface changes can be gradual, occurring over months or years with consistent winds, or rapid during sandstorms, and often involve multiple processes like weathering breaking down rocks into sand. Understanding dune dynamics helps in managing desert environments.
- Two maps show the same river delta where a river meets a lake. In the later map, the shoreline near the river mouth has extended farther into the lake, and new small branching channels appear. Which claim about surface change is supported by the maps? (More than one process may contribute to surface change over time.)
Answer: Sediment was deposited at the river mouth, building the delta outward into the lake over time.
This question requires using map evidence to explain how sediment deposition changes Earth's surface at river mouths. Earth's surface changes as rivers transport sediment from upstream areas and deposit it where they meet standing water bodies. When rivers enter lakes or oceans, their flow velocity decreases, causing suspended sediment to settle out and build deltas that extend into the water body. By comparing maps from different times, you can observe how deltas grow outward and develop branching distributary channels. Some people mistakenly think shorelines only change through erosion, but deposition is equally important in building new land. Surface changes at deltas occur continuously as each flood brings new sediment. Understanding deltaic processes explains how some of the world's most fertile agricultural lands formed and continue to grow.
- Two maps show the same river bend at two different times (Time 1 and Time 2). On the Time 2 map, the river channel has shifted toward the outside of the bend, and a small sandbar appears on the inside of the bend. Multiple processes can contribute to surface change over time.
Based on the maps, which process best explains the change at this river bend?
Answer: Flowing water eroded the outside bank and deposited sediment on the inside bank
The core skill is using evidence from maps to explain changes in Earth's surface. Earth's surface changes over time due to natural processes acting on landforms like rivers. Processes such as erosion by flowing water remove material from one area, while deposition adds sediment elsewhere, causing observable shifts in river bends and the formation of sandbars. To check for such changes, compare the positions of river channels, banks, and new features like sand deposits across maps from different time points. A common misconception is that river paths are static or change only instantly through events like earthquakes, but many shifts occur gradually through water action. Surface changes can be gradual, like slow meander migration, or more rapid during floods. Often, multiple processes, including weathering and sediment transport, interact to reshape landscapes over time.
- Two maps show a mountain slope at two different times after heavy rainfall events. The later map shows a new fan-shaped deposit at the base of the slope and a fresh scar on the hillside. Which claim about surface change is supported by the maps? (More than one process can change slopes over time.)
Answer: Material moved downhill and was deposited at the base, consistent with a landslide or debris flow.
This skill involves using map evidence to explain how gravity-driven processes change Earth's surface. Earth's surface is constantly being reshaped by various forces, including gravity pulling loose material downslope. When heavy rainfall saturates soil and rock on steep slopes, the material can suddenly give way and move downhill as a landslide or debris flow, creating fan-shaped deposits at the base. To identify these changes, look for fresh scars on hillsides and new accumulations of material below. A common misconception is that solid ground never moves naturally, but gravity-driven mass movements are common processes that shape mountainous terrain. Surface changes can occur suddenly during storms or gradually as material creeps downslope. Multiple factors including rainfall, slope angle, and rock type determine when and how slopes fail.
- A city park map shows the same small stream channel at two times. At Time 1, the stream is narrow and straight. At Time 2, the stream is wider with a curved bend, and a small deposit of sediment appears on the inside of the bend. A student says, "The stream changed only because people must have dug a new channel." Multiple processes can contribute to surface change over time.
Which statement is the best evaluation of the student's claim using the evidence from the maps?
Answer: The maps support natural erosion and deposition by flowing water, so human digging is not the only possible explanation
The core skill is using evidence from maps to explain changes in Earth's surface. Earth's surface changes over time, even in managed areas like parks where streams can evolve naturally. Processes such as erosion and deposition by water widen channels and form bends with sediment deposits, causing observable shifts without human intervention. To check for these changes, compare stream shapes, widths, and new deposits across maps from different times. A common misconception is that all stream changes are instant or human-caused, but natural flows often reshape them gradually. Surface changes can be gradual, like slow widening, or rapid during events. Often, multiple processes, including water flow and sediment transport, contribute to landscape modifications over time.
- Two maps show the same desert edge at two different times. The later map shows that a field of sand dunes has shifted so the dunes are now partly covering a road that was clear in the earlier map. What change is most likely next if the same process continues? (More than one process can change Earth's surface over time.)
Answer: The dunes will continue to migrate in the same general direction and may cover more of the road through deposition by wind.
This skill involves using evidence to predict future surface changes based on observed patterns. Earth's surface is constantly changing through processes like wind erosion and deposition in desert environments. When sand dunes migrate, they move in consistent directions determined by prevailing winds, with sand being eroded from the windward side and deposited on the leeward side. By comparing maps over time, you can determine the direction and rate of dune movement to predict where they will likely move next. A common misconception is that sand dunes are permanent features, but they are actually dynamic landforms that continuously shift position. Surface changes in desert environments can be gradual during calm periods or rapid during windstorms. Multiple factors including wind patterns, sand supply, and obstacles influence how dunes form and migrate across landscapes.
- Two maps show the same coastal inlet at two different times. The later map shows the inlet is more filled in with sand/mud, and the water area inside the inlet is smaller. Which process best explains this change over time? (Multiple processes can contribute to surface change.)
Answer: Deposition of sediment carried by rivers and tides gradually filled part of the inlet.
This question tests your ability to use evidence to explain how sediment fills coastal water bodies. Earth's surface changes as rivers and tides transport sediment into sheltered coastal areas where calm water allows particles to settle out. When comparing maps of coastal inlets over time, decreasing water area and expanding mudflats or marshes indicate active deposition is filling the inlet. To identify this process, look for changes in water-land boundaries and new sediment accumulations in formerly open water areas. A common misconception is that coastlines only change through sea level rise or fall, but sediment deposition can dramatically alter coastal geography. Surface changes in coastal environments result from the interaction of river sediment supply, tidal currents, and wave energy. Multiple processes work together to fill inlets, creating new land that may eventually support vegetation and wildlife.
- Two maps show the same river along a town. In the later map, the river is wider in several places and the outside banks of bends have moved outward. Which evidence-based explanation best fits the change over time? (More than one process can shape the river over time.)
Answer: Erosion by flowing water removed material from the outer banks of bends, widening the channel in places.
This skill requires using map evidence to explain how flowing water reshapes river channels. Earth's surface changes as rivers erode their banks, particularly on the outside of bends where water flows fastest and exerts the most force. When comparing river maps from different times, widening channels and outward migration of meander bends indicate active erosion removing bank material. To analyze these changes, measure channel width at multiple points and note which banks have shifted position. Some people mistakenly think rivers maintain constant dimensions, but channel geometry naturally adjusts to changing flow conditions. Surface changes in river systems reflect the balance between erosion and deposition occurring simultaneously at different locations. Understanding river dynamics helps explain why structures near rivers require setbacks and why floodplains exist.
- Two maps of the same river valley are shown: Map A (Older) and Map B (Newer). In Map B, the river channel has shifted to the outside of a bend, and a crescent-shaped lake appears where the river used to flow. Which claim about surface change is supported by the maps? (More than one process can shape river valleys.)
Answer: The river eroded the outside bank and deposited sediment on the inside bank, eventually leaving an oxbow lake
The core skill in studying Earth's changing surface is using evidence from maps or images to explain how and why the surface changes over time. Earth's surface is not fixed but changes continuously due to natural processes acting on landforms like river valleys. Processes such as erosion on outer bends and deposition on inner bends can reshape river channels, leading to features like oxbow lakes as the river meanders and cuts off old loops. To check for changes, compare features like channel positions or new lakes across maps from different time points to trace shifts in the river's path. A common misconception is that rivers change instantly in one event, but most shifts happen gradually through ongoing erosion and deposition rather than sudden, complete alterations. Surface changes can be gradual, building up over seasons or years, or rapid during floods, and often involve multiple processes like weathering contributing to the overall transformation. Recognizing these patterns aids in understanding river valley evolution.
- The map shows a hillside with several small gullies at two time points (Earlier and Later). The gullies are longer and more connected at the Later time point. Which evidence-based explanation best fits the observed change?
Answer: Running water eroded the soil and rock, extending the gullies downhill over time.
This skill focuses on using evidence to explain how Earth's surface changes through erosional processes. Earth's surface is continuously modified by water flow, which creates and enlarges erosional features like gullies over time. Running water erodes soil and rock by carrying particles downhill, extending gullies both in length and depth as the erosion progresses headward and downward. To analyze this change, compare gully patterns between time points and observe how they've grown longer and more interconnected. A misconception is that hillsides cannot change naturally or that weathering alone moves material without erosion. In reality, gully formation requires flowing water to physically transport weathered material downslope. This process can be gradual during light rains or rapid during heavy storms, with multiple factors like slope angle and vegetation affecting erosion rates.
- A map shows a hillside with exposed bedrock at two times: Time 1 (Older) and Time 2 (Newer). At Time 2, the exposed bedrock area is larger, and the soil layer shown on the map is thinner in several places. Which process best explains the change? (More than one process can act together.)
Answer: Erosion removed soil from the slope, exposing more bedrock over time
The core skill in studying Earth's changing surface is using evidence from maps or images to explain how and why the surface changes over time. Earth's surface is not fixed but changes continuously due to natural processes acting on landforms like hillsides. Processes such as erosion can remove soil layers, exposing more bedrock and thinning the soil cover in affected areas. To check for changes, compare features like exposed rock areas or soil thickness across maps from different time points to detect material loss. A common misconception is that bedrock exposure happens instantly, but it often results from gradual erosion rather than sudden events. Surface changes can be gradual through steady weathering or rapid during heavy rains, and often involve multiple processes like deposition elsewhere. This understanding aids in soil conservation efforts.
- The map shows a river valley cross-section location marked on a valley floor at two time points (Earlier and Later). The river channel is wider at the Later time point. Which process best explains the widening shown over time?
Answer: Erosion by moving water that wears away the banks and carries sediment away.
This question requires using evidence to explain how Earth's surface changes through natural processes. Earth's surface continuously transforms as water and other agents reshape landforms over time. River channels widen primarily through erosion, where flowing water wears away the banks and carries sediment downstream, gradually expanding the channel width. To verify this process, compare channel widths at different time points and recognize that widening requires removal of bank material. A common misconception is that deposition makes channels wider or that weathering alone can transport material. Actually, channel widening results from erosive forces that physically remove and transport bank material. This process can occur gradually during normal flow or rapidly during floods, demonstrating how surface change rates vary with conditions and multiple factors influence channel evolution.
- A map shows the same sandy area at two times (Time 1 and Time 2). At Time 2, a field of dunes has shifted east, and some dunes now cover part of a nearby road. What change is shown, and what process most likely caused it? (More than one process can change deserts.)
Answer: The dunes moved east because wind transported sand and deposited it in new places
This question tests your skill in using map evidence to explain how desert surfaces change over time. Earth's surface constantly transforms through natural processes that move and reshape materials. Wind is a powerful agent in deserts, picking up loose sand particles and transporting them across the landscape, building and moving dunes through continuous erosion and deposition. To analyze surface changes, compare dune positions between time periods and note the direction of movement. A common misconception is that sand dunes are permanent features, but they actively migrate as wind patterns shift sand grain by grain. Desert surface changes can be gradual, with dunes creeping meters per year, or rapid during major windstorms. Multiple processes including wind erosion, transportation, and deposition work together to create the ever-changing patterns of desert landscapes.
- Map 1 (Older) and Map 2 (Newer) show the same stretch of coastline. On Map 1, the shoreline is mostly straight. On Map 2, a curved sandy spit extends outward and a shallow lagoon appears behind it. Based on the maps, which process best explains the change over time? (More than one process can change coastlines.)
Answer: Deposition of sand moved by waves and currents built the spit and partly enclosed the lagoon
The core skill in studying Earth's changing surface is using evidence from maps or images to explain how and why the surface changes over time. Earth's surface is not fixed but changes continuously due to natural processes acting on landforms like coastlines. Processes such as deposition by waves and currents can build new features like sandy spits by moving and accumulating sediment, creating observable differences in shoreline shapes. To check for changes, compare specific features like shoreline positions or enclosed areas across maps from different time points to identify additions or shifts. A common misconception is that coastlines are static and unchanging, but they are dynamic and can evolve gradually through sediment transport rather than remaining permanent. Surface changes can occur gradually over years through repeated wave action or more rapidly during storms, and often involve multiple processes like erosion and deposition working together. Understanding these interactions helps predict future coastal developments.
- A map shows the same cliffed coastline at two times. At Time 1, a footpath runs near the cliff edge. At Time 2, the cliff edge is farther inland in several places, and broken rock is shown at the base of the cliff. Multiple processes may contribute to surface change over time.
Which process best explains the change shown?
Answer: Wave action and weathering weakened the cliff, leading to erosion and rockfall
The core skill is using evidence from maps to explain changes in Earth's surface. Earth's surface changes over time, with cliffs retreating due to exposure to elements. Processes like wave action and weathering weaken rock, leading to erosion and rockfalls that move cliff edges inland and deposit debris below. To check for such changes, compare cliff positions, paths, and base materials across maps from different time points. A common misconception is that cliffs are static or move due to continental shifts, but local erosion often causes gradual retreat. Surface changes can be gradual, like ongoing weathering, or rapid during storms. Often, multiple processes, including physical and chemical breakdown, contribute to coastal cliff transformations over time.
- Two maps show the same volcanic area before and after an eruption. In the later map, a dark new surface covers part of the older ground and blocks a small stream. Which process best explains the change shown over time? (More than one process can change Earth's surface over time.)
Answer: A lava flow spread over the land surface and created new rock that covered older features.
This question tests your ability to use evidence to explain how volcanic processes change Earth's surface. Earth's surface changes through both gradual and sudden processes, including volcanic eruptions that can dramatically alter landscapes. When volcanoes erupt, they often produce lava flows that spread across the land, creating new rock surfaces that cover and preserve older features beneath. By comparing maps before and after eruptions, you can trace the extent of new volcanic deposits and see how they block streams or bury vegetation. Some people incorrectly think that only erosion changes surfaces, but volcanic deposition adds new material that builds up the land. Surface changes from lava flows happen relatively quickly as molten rock cools and solidifies. Understanding volcanic processes helps explain why some areas have layers of different-aged rocks and how new land forms.
- Two maps show the same stream valley at two times. The older map shows a narrow stream and a small floodplain. The newer map shows a wider floodplain with a new layer of light-colored sediment covering part of the valley floor. Multiple processes can contribute to surface change over time.
Which claim is incorrect based on the evidence in the maps?
Answer: No deposition happened because streams only erode and never leave sediment behind
The core skill is using evidence from maps to explain changes in Earth's surface. Earth's surface changes over time, with stream valleys evolving through water-related actions. Processes like flooding lead to deposition of sediment, widening floodplains and adding new layers, causing observable expansions in valley features. To check for these changes, compare stream widths, floodplain sizes, and sediment deposits across maps from different times. A common misconception is that streams only erode without depositing material, but they often do both, sometimes gradually. Surface changes can be gradual, like slow sediment buildup, or rapid during floods. Often, multiple processes, such as upstream erosion and downstream deposition, interact to reshape valleys over time.
- A map shows the same barrier island at two times (Earlier and Later). In the Later map, the island is thinner in the middle, and a new opening (inlet) connects the ocean to the lagoon behind the island. Which explanation is best supported by the map evidence? (More than one process can change barrier islands.)
Answer: Waves and storm surge likely eroded and moved sand, opening an inlet and reshaping the island
This question requires using map evidence to explain how barrier islands change during storm events. Earth's surface transforms dramatically when powerful storms impact coastal areas, reshaping sandy islands through intense wave action and storm surge. Storm waves and surge can erode sand from island surfaces, transport it elsewhere, and cut new channels (inlets) completely through narrow sections, connecting ocean and lagoon waters. To identify storm impacts, compare island width and look for new openings that weren't present before. A common misconception is that islands change only through gradual processes, but single storms can dramatically alter or breach barrier islands. Barrier island changes can be gradual through daily wave action or catastrophic during hurricanes and nor'easters. Multiple processes including wave erosion, overwash, and inlet formation work together to continuously reshape these dynamic coastal barriers.
- A map shows a river delta at two times (Time 1 and Time 2). At Time 2, the land at the river mouth extends farther into the lake, and new branching channels appear. If the same main process continues, what change is most likely next? (More than one process can affect deltas.)
Answer: The delta will keep building outward as the river deposits more sediment at the mouth
This question requires using map evidence to predict future changes in river deltas based on observed patterns. Earth's surface changes predictably when the same processes continue operating over time. River deltas grow through continuous deposition as rivers carry sediment to their mouths, where slower water drops its load, building new land outward into water bodies. To predict future changes, identify the dominant process from past observations and project its continuation. A common misconception is that deposition happens only once, but rivers continuously transport and deposit sediment as long as they flow. Delta growth can be gradual over years or accelerated during floods when sediment loads increase. Multiple processes including sediment transport, deposition, and channel splitting work together to build these dynamic coastal features that expand seaward over time.
- Two maps show the same river mouth (delta) at two times. On the older map, the river meets the sea with a small delta. On the newer map, the delta extends farther into the sea with new land-shaped lobes, and the main channel splits into more branches. Multiple processes can contribute to surface change over time.
What change is shown in these maps?
Answer: The delta built outward as sediment was deposited where the river slowed near the sea
The core skill is using evidence from maps to explain changes in Earth's surface. Earth's surface changes over time, especially at river mouths where land meets sea. Processes like sediment deposition build deltas outward, creating new land and branching channels as rivers slow and drop material. To check for these changes, compare delta extents, channel splits, and new land areas across maps from different times. A common misconception is that deltas are static or shrink naturally, but they often grow gradually through deposition. Surface changes can be gradual, such as steady buildup, or rapid after heavy rains. Often, multiple processes, including erosion upstream and wave redistribution, shape deltas over time.
