Understanding Geological Processes and Their Impact on Relief
Sculpting the Relief · Mountains, rivers, glaciers, and wind modify the relief, acting as geological agents. These processes are activated by solar energy, which favors the evaporation of water and allows for rain and gravity to play their roles. External geological agents and actions are involved in these processes, while internal processes are caused by the heat inside the Earth. Factors Affecting Relief Shape. Land surface processes take form through the modeling of the relief: • Each type of rock has unique characteristics. The Climate · External geological areas are determined by climate, including ice and warm water. The Structure of the Materials · Folded or fractured rocks provide various forms. The Age of the Relief · The landscape changes over time.
Influence of Rock Type. Rocks are materials that model the relief, with existing rock types in each area affecting shape and form. Very cohesive rocks are easier to erode, while less cohesive rocks are more resistant to erosion.
Clay Relief. These are slightly cohesive sediments and rocks that are waterproof and easily eroded. Plains and low reliefs cover most of the Iberian Peninsula. In arid climates, there is little vegetation. Torrential rains can create gullies and canyons, leading to badlands.
Stochastic Relief. Reliefs caused by the dissolution of limestone or similar rocks form through the action of water dissolving the limestone, creating grooves or cliffs. In some places, sinkholes are circular or oval depressions that arise from the dissolution of limestone. Limestone is very permeable, and water does not filter through cracks and bedding planes. As water flows, it dissolves the limestone, creating risers, pits, and horizontal galleries. Narrowing of a gallery can form caves. Vaults are created by water leaks. Water contains dissolved limestone, and every drop leaves a small part of it behind. Stalactites are formed as water drips to the floor, creating stalagmites. The growth of stalactites and stalagmites can lead to the formation of columns.
Granitic Terrain. Granite is a rocky material composed of quartz, feldspar, and mica, with recognizable embossing. • It has resistance to natural weathering but is vulnerable to chemical processes. · The number of cracks or joints in horizontal and vertical planes divides it into cubic blocks. Evolution: 1. Water enters the joints, initiating the chemical process. It is more pronounced in the corners where there is more surface contact. 2. Effects include the formation of gravel, originating from the chemical processes between the blocks. This leads to the formation of bowling. The volume of the blocks is reduced, resulting in rounded shapes. 3. Rounded blocks can stack, forming what is known as bowling chaos. Beneath the residual sand lies the bowling landscape, characterized by chaotic crags.
Climatic Influences. Each geological agent is influenced by climatic conditions. Surface Water. Continental, warm weather, and tropical climates contribute to the formation of aggregates. Marine. Oceanic and coastal influences also play a role. Wind. Contributes to the formation of coastal aggregates. Glaciers. Glacial and periglacial processes also occur. In addition to these agents, material movements due to gravitational processes are significant.
Gravity Processes. The displacement of matter occurs due to the action of gravity without any intermediate agent. Detachment. The fall of materials, either wholly or partially, caused by collapse or backsliding. Slippage. The sliding of materials locked on a sliding surface, maintaining contact with the surface while keeping their shape during the slip. Flow. The mass movement of materials that are forced off, such as clayey mud, which changes shape during displacement. Creeping. The slow displacement of loose material beneath the surface layer, which is often not observable.
The surface where there is a slope encompasses a highly efficient transport system.
Modeling of Surface Guides. Rainfall leads to three scenarios: evaporation, infiltration, and runoff. Surface waters do not drive wild waters. Streams and rivers are interconnected. Water removes materials from highlands and deposits them in lower areas. Forms of Erosion: The erosive capacity increases with speed and flow. · Differential erosion creates various features. Cliffs and Waterfalls are formed through alternating water flow. Gullies and Ravines expand and deepen, creating a hierarchical network: a groove path where the most prominent flows into a larger one. V-shaped Valleys are formed by rivers in their channels. Trough Valleys are created as gravitational forces move materials from the bottom, widening the valley and allowing water to cover a larger floodplain. Depositional Forms: When the flow decreases, it loses power and stops transporting materials. Alluvial Fans are accumulations of materials transported by streams that are deposited as they reach flat areas. Floodplains are deposits created by rivers during floods, forming flat river valleys. Combined Forms: Loops. Curves described by rivers. Differences in flow rates lead to erosion on the outer edge of curves, while sedimentation occurs on the inner bank where the speed is reduced. River Terraces. Ancient river floodplains that have been excavated in sediments and left far below them.
Modeling Glaciers. A glacier is a large mass of ice that shapes the Earth’s surface. They can be found in polar regions, ice caps, and mountain valleys. Three areas are identified: the Circus – the highest area where snow and ice accumulate; the Lengies – the mass of ice that flows down the valley; and the Terminal Zone – where ice deposits materials.
Forms of Erosion: The erosive capacity is due to the mass of ice and rock fragments that act as carrying agents: Alpine U-shaped Valleys are formed by glacial action. Hanging Valleys are tributary valleys of ancient glaciers. Glacial Lagoons are formed in over-excavated beds, resulting in deeper bottoms where melted ice creates mountain lakes. Sedimentation occurs through deposits forming moraines: Front or Terminal Moraine – the front of the glacier; Side Moraines – located on both sides of the glacier tongue; and Central Moraines – formed between two lateral moraines.