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ESO Y4B · Biology and Geology
The dynamic Earth · The history of the Earth

Relief and landscape

A mountain range rising up and the canyon cutting through it seem like opposing processes: one builds, the other excavates. In reality they are two sides of the same phenomenon, because all relief results from a permanent tug-of-war between forces that uplift and forces that wear away.

Before you start, make sure you know: The shaping of relief (3rd ESO)
Before you start, make sure you know: The lithosphere and its materials (1st ESO)

Relief: a balance between internal and external processes

When we look at a mountain range, we see rugged peaks thousands of metres high alongside deep ravines and slopes covered in fallen blocks. What forces are capable of lifting millions of tonnes of rock up to the clouds while the atmosphere and water relentlessly try to break them down?

Cross-section of a mountain range. The collision of plates folds and uplifts the rocks, which are internal processes. Rain, weathering, erosion, transport and sedimentation wear away and shape the relief, which are external processes. folds plate collision uplift rain weathering erosion transport sedimentation Internal processes: uplift External processes: wear away
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Name four external geological agents that shape the relief and give an example of a landform created by each one.

Name four external geological agents that shape the relief and give an example of a landform created by each one.

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Explain the difference between erosion, transport and deposition, and order them as they occur in landform shaping.

Explain the difference between erosion, transport and deposition, and order them as they occur in landform shaping.

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Lithology influences how relief is shaped

Comparison of two cross-sections of the terrain: in limestone, water seeps through the fractures and forms a sinkhole, a shaft and a cave with stalactites and stalagmites; in granite, the joints isolate rounded blocks that remain on the surface as the boulders of a berrocal. Limestone · karst relief Granite · berrocales water sinkhole shaft cave boulders joints
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State whether these landforms were mainly shaped by water, ice or wind: a U-shaped valley, a dune, a river canyon and a moraine.

State whether these landforms were mainly shaped by water, ice or wind: a U-shaped valley, a dune, a river canyon and a moraine.

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Two regions with the same climate have very different landscapes because one consists of limestone rock and the other of granite. Explain how lithology (rock type)…

Two regions with the same climate have very different landscapes because one consists of limestone rock and the other of granite. Explain how lithology (rock type) influences landform development and what characteristic relief limestone typically creates.

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Shaping agents: river and glacial landforms

In the Pyrenees we find flat-bottomed valleys where whole villages sit, while in other massifs rivers run through narrow gorges where there is barely room for the channel. Why do two agents shaping the same mountain produce such radically different valley forms?

Comparative cross-sectional profiles: above, a narrow V-shaped river valley with steep walls, with the river cut into the floor by vertical erosion; below, a wide U-shaped glacial valley with a flat floor, with the former glacier, lateral and basal erosion, lateral moraines and an erratic block. River valley (V-shaped profile) vertical erosion steep walls river channel Glacial valley (U-shaped profile) former glacier lateral and basal erosion lateral moraine lateral moraine wide, flat floor erratic block
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Look at the cross-sectional profiles of the two valleys in the diagram, marked with ?. Identify which is a river valley and which is a glacial valley, explain which…

Look at the cross-sectional profiles of the two valleys in the diagram, marked with ?. Identify which is a river valley and which is a glacial valley, explain which agent shaped each one, and what differences in shape allow them to be distinguished.

Valley A ? Valley B ?
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The value of relief: scientific, scenic and economic

Landscape in profile with a mountain of layered rocks, on whose flank a stepped quarry with a lorry has been excavated, a valley with fertile soil, crops and a river, and on the right a relief with a distinctive rock formation and a viewpoint with an information board for geotourism. i quarry rocks and minerals fertile valley fertile soils geotourism landscape and heritage strata: record of geological history
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Relief is also a resource. Describe two economic uses of relief (for example, tourism or agriculture) and a risk associated with each.

Relief is also a resource. Describe two economic uses of relief (for example, tourism or agriculture) and a risk associated with each.

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A municipality with an old mining basin in economic decline has a unique karst landscape with prehistoric caves, tectonic folds of great educational value, and several…

A municipality with an old mining basin in economic decline has a unique karst landscape with prehistoric caves, tectonic folds of great educational value, and several threatened botanical species. The city council is debating between two protection designations:

  • Option A: Declare the area a National Park with strictly restricted access for scientific research.

  • Option B: Apply for its declaration as a UNESCO Global Geopark.

  1. a) Justify why the Geopark model is better suited to this case than the National Park model if the goal is to reconcile the protection of geological heritage with the socioeconomic development of the local population.
  2. b) Design two specific geotourism management measures that the geopark should implement so that public visits do not alter or degrade the karst cavities.
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In Las Médulas (León), Roman mining transformed the landscape through the technique of ruina montium* (violent injection of pressurised water into galleries to collapse…

In Las Médulas (León), Roman mining transformed the landscape through the technique of ruina montium (violent injection of pressurised water into galleries to collapse hillsides), generating alluvial fans of boulders, mudflats, and the natural dam of Lake Carucedo. Today it is a protected landscape designated as a UNESCO World Heritage site.

  1. a) Analyse human intervention as an external geological agent in Las Médulas, identifying the stages of erosion, transport, and sedimentation artificially caused by the mining technique.
  2. b) A current mining company requests permission to open-pit mine a nearby pristine valley, arguing that "human activity creates landscapes that in the future will also be considered historical heritage like Las Médulas". Technically refute this argument by comparing the rate of landscape alteration, the toxicity of modern techniques, and the possibility of ecological regeneration.
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The relief of the Iberian Peninsula and its sustainable management

If we cross Spain from Santander to Seville, we go from high coastal peaks to a flat plateau raised more than $600\text{ m}$ above sea level, and after crossing Sierra Morena we descend to a great plain almost at sea level. What tectonic history explains why the relief of the peninsula is arranged as a central plateau surrounded by walls of mountains and river basins?

Schematic north–south cross-section of the Iberian Peninsula: the Cantabrian Mountains, the Meseta with the Central System, Sierra Morena, the Guadalquivir depression and the Betic Ranges, showing the interior basement, the outer mountain ranges and the sedimentary basin. N S North–south cross-section (vertical scale exaggerated) Cantabrian Mountains Northern north Central System (interior mountain range) Southern south Sierra Morena Betic Ranges interior basement (Meseta) faults Guadalquivir Depression Interior basement (Meseta): ancient, rigid, fractured block Outer mountain range: young, folded in the Alpine orogeny Sedimentary basin: material eroded from the mountain ranges
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Imagine a geological and topographical cross-section running across the Iberian Peninsula from north to south: the Cantabrian Mountains, the Douro Basin, the Central…

Imagine a geological and topographical cross-section running across the Iberian Peninsula from north to south: the Cantabrian Mountains, the Douro Basin, the Central System, the Tagus Basin, and the Betic Cordillera.

  1. a) During the Alpine orogeny, why did the ancient Hercynian basement of the central peninsula respond by fracturing into uplifted blocks (horsts) and down-dropped blocks (grabens), whereas on the edges (Cantabrian and Betic ranges) large folded mountain chains formed? Justify your answer based on the mechanical behaviour of the materials in each area.
  2. b) Predict the origin and geometric arrangement (horizontal or folded) of the materials that fill the Douro and Tagus basins, deducing which mountain ranges they come from and what geological process caused their accumulation.
Solve

Summary

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