Geological Processes
Geological processes refer to the natural forces and phenomena that shape the Earth's surface over time. These processes include tectonic plate movements, erosion, weathering, and volcanic activity. They play a crucial role in forming landforms, such as mountains, valleys, and coastlines, and contribute to the overall physical geography of the Earth.
4 Key excerpts on "Geological Processes"
eBook - ePub- Simon Bell(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...Introduction The previous chapter showed how climate, particularly the aftereffects of the last (but probably not the final) glaciations, has driven and continues to drive many changes occurring in the landscape. The landform patterns and processes which are the subject of this chapter are no exception to this, and in fact in them we can see both the results of climatic processes and their continuing role in modifying climatic processes in the short to medium term, such as volcanic eruptions throwing gas and dust into the atmosphere. The structure and processes of geology supply the basic underlying layer or substrate upon which all terrestrial life and human activities rely. Geology interacts directly with climate to maintain a continuously dynamic state. However, the rates of geological change are generally so slow that for most ecological processes, or considerations for human use, it supplies a relatively stable framework and sets limits or boundary conditions. Areas of ancient shield rocks, where erosion is extremely slow, possess extremely stable geologies. There are places in which dramatic processes occur reasonably frequently, notably in regions with active volcanoes and earthquakes, where processes can disturb and modify ecological or cultural patterns quite dramatically, and occasionally disastrously for anyone living there. It is not the purpose of this chapter to provide a primer on geology, geomorphology or hydrology; instead it is to interpret what we perceive in this field in terms of the patterns and processes, insofar as they help us to read the landscape and to give us a basis for understanding the ecological and human patterns superimposed upon it...
eBook - ePubHydrogeology
Principles and Practice
- Kevin M. Hiscock, Victor F. Bense(Authors)
- 2021(Publication Date)
- Wiley-Blackwell(Publisher)
...3 Groundwater and Geological Processes 3.1 Introduction This chapter discusses the response of groundwater systems to Geological Processes such as plate tectonics, glaciation and sea‐level fluctuations. Although topography‐driven groundwater flow, as introduced in Chapter 2, is in many areas of the world the dominant mode of groundwater circulation, consideration of the additional impact of Geological Processes on groundwater flow is often important to fully appreciate the dynamics of groundwater systems on relatively long timescales (millennia). For example, only by considering the hydrogeological impacts of glaciation and associated sea‐level low stand, can the occurrence of fresh water underneath the sea‐floor along much of the continental shelf be understood. In the description of regional groundwater flow systems, which typically reach circulation depths of several kilometres, flow driven by the variable density of groundwater and flow induced by stresses imposed on pore fluids play an important role and often form the sole driver of fluid flow in the absence of topographically driven flow. The variable density of groundwater and anomalous pore pressures can be caused by a suite of Geological Processes. Thus, to understand fluid flow patterns in relatively deep hydrogeological systems requires an understanding of how the relevant Geological Processes cause fluid flow. It is the task of the hydrogeologist to evaluate, for a given geological setting, which processes can be expected to be dominant in driving fluid flow in the subsurface. The way groundwater and other geofluids, such as hydrocarbons, respond to geological forcing often has a direct feedback on how Geological Processes proceed. This feedback mechanism is, for example, important when the influence of fluids on seismicity should be considered...
eBook - ePub- Supriya Sengupta(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...2 PROCESSES OF SEDIMENTATION SURFACE PROCESSES AND ROCK WEATHERING Sedimentary processes are largely controlled by just two agencies, water and wind. Thus the hydrological and wind cycles play very important roles in sedimentation. The hydrological cycle is schematically represented in Fig. 2.1. About two-thirds of the precipitation that takes place on land finds its way back to the atmosphere through evaporation and transpiration. The rest flows back to the sea mostly as surface run-off through streams and partly as ground-water. The actual amount of water involved in the different phases of movement varies from place to place, depending on local geography and climate but by and large a balance in the water budget is maintained. Water is also responsible to a large extent for weathering and decomposition of pre-existing igneous, metamorphic and sedimentary rocks. The actual amount of sediment yield depends not only on precipitation, but also on surface conditions, types of rocks exposed and density of vegetation cover. Rock weathering can take place by mechanical, chemical and biological actions. Freezing of water percolating into fractures and joints of rock bodies causes expansion and disintegration in cold climate (frost heaving). Fig. 2.1: Schematic representation of the hydrological cycle. The balance between evaporation and precipitation in an ideal tropical region is indicated by arrows. The figures within the circles (modified after Siever 1983) give an approximate idea of the proportion of water flow per year. Earthquakes, the heat of lightning and the impact between large bodies of displaced rock masses are some of the other causes of mechanical disaggregation. In drier climate, crystallisation of soluble salts within cracks and fissures can disrupt rock bodies. Mechanical abrasion and deflation are important erosive processes in deserts. Much of the actual disintegration of rocks takes place by chemical weathering...
eBook - ePubIntegrated Reservoir Asset Management
Principles and Best Practices
- John Fanchi(Author)
- 2010(Publication Date)
- Gulf Professional Publishing(Publisher)
...The beginning of the cycle occurs with the cooling of molten magma and subsequent hardening into rock. Typically, the formation of new rock occurs at plate boundaries, but it can also occur over “hot spots” within the earth’s mantle. As plates collide, pressure and heat may cause part of the plate to melt and result in molten rock being thrust to the surface. After cooling, surface rock is subjected to atmospheric phenomena. Chemical and physical processes cause exposed rock to break into smaller and smaller particles. Wind and water transport these particles from their source location in a process called erosion. The particles become finer as they collide with other objects during the transport process. A particle will be deposited along with other particles when the energy of the wind or water dissipates to the point where there is not enough energy to transport the particle. The accumulation of particles thickens as particles are deposited in a specific location. Slowly—over millions of years—tectonic plates move up and down relative to sea level, alternately causing erosion and deposition. Deposition can range from thousands of feet of sediment in an area to none at all. Erosion can carve canyons, level once jagged mountains, or remove all traces of a formation that was once hundreds of feet thick. High pressure and temperature can cause rocks to change character in a process called metamorphism. Particles may become fused together to form considerably larger objects. Given enough time, pressure, and heat, rocks will melt and start the cycle again. Based on this rock cycle, geologists recognize three primary types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks are formed by the cooling of material that has been molten. Sedimentary rocks form when materials at the surface of the earth are weathered, transported, deposited, and cemented together...
