Investigations have focused on individual hazards but it is also possible to envisage the way in which a combination of hazards can contribute to the hazardousness of a place. Geomorphic contributions have mapped and modelled hazards, analysed vulnerability hazard and risk, and suggested management options including those for the prevention of natural disasters. Particular studies have been made in drylands including desertification, as well as in urban areas. Future potential includes improvement in our understanding of geomorphic hazards by research into the characteristics of hazard events and predicting CQ Press Your definitive resource for politics, policy and people.
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View purchasing options. Find in this title Show Hide Page Numbers. On This Page. Copy to Clipboard. Looks like you do not have access to this content. The study of landforms and the evolution of the Earth's surface can be dated back to scholars of Classical Greece. Herodotus argued from observations of soils that the Nile delta was actively growing into the Mediterranean Sea , and estimated its age.
He claimed that this would mean that land and water would eventually swap places, whereupon the process would begin again in an endless cycle. Another early theory of geomorphology was devised by the polymath Chinese scientist and statesman Shen Kuo — This was based on his observation of marine fossil shells in a geological stratum of a mountain hundreds of miles from the Pacific Ocean.
Noticing bivalve shells running in a horizontal span along the cut section of a cliffside, he theorized that the cliff was once the pre-historic location of a seashore that had shifted hundreds of miles over the centuries. He inferred that the land was reshaped and formed by soil erosion of the mountains and by deposition of silt , after observing strange natural erosions of the Taihang Mountains and the Yandang Mountain near Wenzhou.
The term geomorphology seems to have been first used by Laumann in an work written in German. McGee used it during the International Geological Conference of An early popular geomorphic model was the geographical cycle or cycle of erosion model of broad-scale landscape evolution developed by William Morris Davis between and It was thought that tectonic uplift could then start the cycle over. In the decades following Davis's development of this idea, many of those studying geomorphology sought to fit their findings into this framework, known today as "Davisian".
In the s, Walther Penck developed an alternative model to Davis's. Penck was German, and during his lifetime his ideas were at times rejected vigorously by the English-speaking geomorphology community. Both Davis and Penck were trying to place the study of the evolution of the Earth's surface on a more generalized, globally relevant footing than it had been previously. In the early 19th century, authors — especially in Europe — had tended to attribute the form of landscapes to local climate , and in particular to the specific effects of glaciation and periglacial processes.
In contrast, both Davis and Penck were seeking to emphasize the importance of evolution of landscapes through time and the generality of the Earth's surface processes across different landscapes under different conditions. During the early s, the study of regional-scale geomorphology was termed "physiography". Some geomorphologists held to a geological basis for physiography and emphasized a concept of physiographic regions while a conflicting trend among geographers was to equate physiography with "pure morphology", separated from its geological heritage.
During the age of New Imperialism in the late 19th century European explorers and scientists traveled across the globe bringing descriptions of landscapes and landforms. As geographical knowledge increased over time these observations were systematized in a search for regional patterns. Climate emerged thus as prime factor for explaining landform distribution at a grand scale. William Morris Davis , the leading geomorphologist of his time, recognized the role of climate by complementing his "normal" temperate climate cycle of erosion with arid and glacial ones.
Peltier's publication on a periglacial cycle of erosion. Climatic geomorphology was criticized in a review article by process geomorphologist D. Geomorphology was started to be put on a solid quantitative footing in the middle of the 20th century. Shields , Thomas Maddock , Arthur Strahler , Stanley Schumm , and Ronald Shreve began to research the form of landscape elements such as rivers and hillslopes by taking systematic, direct, quantitative measurements of aspects of them and investigating the scaling of these measurements. These methods began to allow prediction of the past and future behavior of landscapes from present observations, and were later to develop into the modern trend of a highly quantitative approach to geomorphic problems.
Many groundbreaking and widely cited early geomorphology studies appeared in the Bulletin of the Geological Society of America ,  and received only few citations prior to they are examples of "sleeping beauties"  when a marked increase in quantitative geomorphology research occurred.
Quantitative geomorphology can involve fluid dynamics and solid mechanics , geomorphometry , laboratory studies, field measurements, theoretical work, and full landscape evolution modeling. These approaches are used to understand weathering and the formation of soils , sediment transport , landscape change, and the interactions between climate, tectonics, erosion, and deposition. This developed into "the Uppsala School of Physical Geography ".
Today, the field of geomorphology encompasses a very wide range of different approaches and interests. Particularly important realizations in contemporary geomorphology include:. Instead, dynamic changes of the landscape are now seen as an essential part of their nature. Albeit having its importance diminished climatic geomorphology continues to exist as field of study producing relevant research.
More recently concerns over global warming have led to a renewed interest in the field. Despite considerable criticism the cycle of erosion model has remained part of the science of geomorphology. Geomorphically relevant processes generally fall into 1 the production of regolith by weathering and erosion , 2 the transport of that material, and 3 its eventual deposition.
Primary surface processes responsible for most topographic features include wind , waves , chemical dissolution , mass wasting , groundwater movement, surface water flow, glacial action , tectonism , and volcanism. Other more exotic geomorphic processes might include periglacial freeze-thaw processes, salt-mediated action, changes to the seabed caused by marine currents, seepage of fluids through the seafloor or extraterrestrial impact.
Aeolian processes pertain to the activity of the winds and more specifically, to the winds' ability to shape the surface of the Earth. Winds may erode, transport, and deposit materials, and are effective agents in regions with sparse vegetation and a large supply of fine, unconsolidated sediments.
Although water and mass flow tend to mobilize more material than wind in most environments, aeolian processes are important in arid environments such as deserts. The interaction of living organisms with landforms, or biogeomorphologic processes , can be of many different forms, and is probably of profound importance for the terrestrial geomorphic system as a whole. Biology can influence very many geomorphic processes, ranging from biogeochemical processes controlling chemical weathering , to the influence of mechanical processes like burrowing and tree throw on soil development, to even controlling global erosion rates through modulation of climate through carbon dioxide balance.
Terrestrial landscapes in which the role of biology in mediating surface processes can be definitively excluded are extremely rare, but may hold important information for understanding the geomorphology of other planets, such as Mars. Rivers and streams are not only conduits of water, but also of sediment. The water, as it flows over the channel bed, is able to mobilize sediment and transport it downstream, either as bed load , suspended load or dissolved load. The rate of sediment transport depends on the availability of sediment itself and on the river's discharge.
In this way, rivers are thought of as setting the base level for large-scale landscape evolution in nonglacial environments. As rivers flow across the landscape, they generally increase in size, merging with other rivers. The network of rivers thus formed is a drainage system. These systems take on four general patterns: dendritic, radial, rectangular, and trellis. Dendritic happens to be the most common, occurring when the underlying stratum is stable without faulting.
Drainage systems have four primary components: drainage basin, alluvial valley, delta plain, and receiving basin. Some geomorphic examples of fluvial landforms are alluvial fans , oxbow lakes , and fluvial terraces. Glaciers , while geographically restricted, are effective agents of landscape change. The gradual movement of ice down a valley causes abrasion and plucking of the underlying rock. Abrasion produces fine sediment, termed glacial flour.
The debris transported by the glacier, when the glacier recedes, is termed a moraine. Glacial erosion is responsible for U-shaped valleys, as opposed to the V-shaped valleys of fluvial origin. The way glacial processes interact with other landscape elements, particularly hillslope and fluvial processes, is an important aspect of Plio-Pleistocene landscape evolution and its sedimentary record in many high mountain environments. Environments that have been relatively recently glaciated but are no longer may still show elevated landscape change rates compared to those that have never been glaciated.
Nonglacial geomorphic processes which nevertheless have been conditioned by past glaciation are termed paraglacial processes. This concept contrasts with periglacial processes, which are directly driven by formation or melting of ice or frost. Soil , regolith , and rock move downslope under the force of gravity via creep , slides , flows, topples, and falls.
Such mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus , Titan and Iapetus. Ongoing hillslope processes can change the topology of the hillslope surface, which in turn can change the rates of those processes. Hillslopes that steepen up to certain critical thresholds are capable of shedding extremely large volumes of material very quickly, making hillslope processes an extremely important element of landscapes in tectonically active areas.
On the Earth, biological processes such as burrowing or tree throw may play important roles in setting the rates of some hillslope processes. Both volcanic eruptive and plutonic intrusive igneous processes can have important impacts on geomorphology. The action of volcanoes tends to rejuvenize landscapes, covering the old land surface with lava and tephra , releasing pyroclastic material and forcing rivers through new paths. The cones built by eruptions also build substantial new topography, which can be acted upon by other surface processes. Plutonic rocks intruding then solidifying at depth can cause both uplift or subsidence of the surface, depending on whether the new material is denser or less dense than the rock it displaces.
Tectonic effects on geomorphology can range from scales of millions of years to minutes or less. The effects of tectonics on landscape are heavily dependent on the nature of the underlying bedrock fabric that more or less controls what kind of local morphology tectonics can shape. Earthquakes can, in terms of minutes, submerge large areas of land creating new wetlands. Isostatic rebound can account for significant changes over hundreds to thousands of years, and allows erosion of a mountain belt to promote further erosion as mass is removed from the chain and the belt uplifts.
Long-term plate tectonic dynamics give rise to orogenic belts , large mountain chains with typical lifetimes of many tens of millions of years, which form focal points for high rates of fluvial and hillslope processes and thus long-term sediment production. Both can promote surface uplift through isostasy as hotter, less dense, mantle rocks displace cooler, denser, mantle rocks at depth in the Earth. Marine processes are those associated with the action of waves, marine currents and seepage of fluids through the seafloor. Mass wasting and submarine landsliding are also important processes for some aspects of marine geomorphology.
Different geomorphological processes dominate at different spatial and temporal scales. Moreover, scales on which processes occur may determine the reactivity or otherwise of landscapes to changes in driving forces such as climate or tectonics. To help categorize landscape scales some geomorphologists might use the following taxonomy :. There is a considerable overlap between geomorphology and other fields.
Deposition of material is extremely important in sedimentology. Weathering is the chemical and physical disruption of earth materials in place on exposure to atmospheric or near surface agents, and is typically studied by soil scientists and environmental chemists , but is an essential component of geomorphology because it is what provides the material that can be moved in the first place. Civil and environmental engineers are concerned with erosion and sediment transport, especially related to canals , slope stability and natural hazards , water quality , coastal environmental management, transport of contaminants, and stream restoration.
Glaciers can cause extensive erosion and deposition in a short period of time, making them extremely important entities in the high latitudes and meaning that they set the conditions in the headwaters of mountain-born streams; glaciology therefore is important in geomorphology.
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From Wikipedia, the free encyclopedia. The scientific study of landforms and the processes that shape them. For the scientific journal, see Geomorphology journal. Further information: Climatic geomorphology.
Main article: Fluvial. See also: Hack's law and Sediment transport. See also: Erosion and tectonics. Bioerosion Biogeology Biogeomorphology Biorhexistasy British Society for Geomorphology Coastal biogeomorphology Coastal erosion Drainage system geomorphology Erosion Erosion prediction Geologic modelling Geomorphometry Geotechnics Hack's law Hydrologic modeling , behavioral modeling in hydrology Orogeny Physiographic regions of the world Sediment transport Soil morphology Soils retrogression and degradation Stream capture Thermochronology Weathering List of important publications in geology.
Geological Society of America, January
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