shore(redirected from Beachline)
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land bordering an ocean or other large body of water. The line of contact between the land and water surfaces is called the shoreline. It fluctuates with the waves and tides.
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a gently sloping zone where deposits of unconsolidated sediments are subject to wave action at the shore of an ocean or lake. Most of the sediment making up a beach is supplied by rivers or by the erosion of highlands adjacent to the coast.
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the strip of interaction between dry land and a body of water (sea, lake, or reservoir) or a current of water (rivers, temporary stream channels). The chief factors in the formation of the shore of a body of water are waves and surf currents; these are manifested most clearly in the coastal zone of a sea.
Seashore (coastal zone). The factors that form the seashore are basically the abrasion and shifting of the accretions that make up various coastal accumulative forms. The role of dry land in the process of interaction with the sea consists in the fact that rivers and other exogenous agents bring the detritus from which coastal and marine accretions are formed from the land to the shore zone; the geological structure and relief of the coastal land influence the course and direction of development of the seashore.
The development of the seashore along accumulative or abrasional lines is determined by the level of energy discharged by the waves over the underwater coastal slope. The latter is a function of the parameters of the waves, the incline of the submerged slope, and the equilibrium of the accretion in the seashore. Large waves (which on the whole can perform more intensive work), great depths over the underwater slope, and a small quantity of accretion on the slope ensure that the waves will not completely expend their energy in passing over the submerged part of a seashore. These conditions facilitate the abrasional process. Small wave parameters, an abundance of accretion, and a gentle underwater slope ensure that the energy expenditure over the underwater coastal slope will be considerable and, correspondingly, that the accumulative process will predominate on the seashore.
The beginning of the formation of the contemporary coastal zone of the seas and oceans dates to the time when, as a result of late Ice Age transgressions, the level of the ocean was established at levels close to those of modern times (5,500–6,000 years ago). In the course of these transgressions, the level of the ocean rose by approximately 90–100 m in comparison with its previous state, as a result of which there was flooding of the outlying plains of the continents and of the lower reaches of subaerial valley forms. Various types of ingressive shores were formed in this process. These can be divided into glacial (fjords, or skerries), erosional (ria, estuary), aeolian (the Aral shore type), structuraldenudational (the Dalmatian type), and other varieties.
The aggregate of abrasional and accumulative processes leads to the smoothing of the contour of ingressive shores: promontories are cut off by abrasion, and inlets are filled in or cut off by coastal accumulative forms. The rate of the process of smoothing of the coast is also determined by the quantity of accretion entering the seashore and the degree of durability of the rocks that make up the native shore. The process of smoothing is at a rudimentary stage where the coastal slopes are made up of strong rocks: such shores have retained the original indentation of their coastal lines—determined by the subaerial relief—to the present day. The following basic types of shore may be distinguished on the basis of the degree and nature of the reworking of the shore by wave processes: those unchanged (or virtually unchanged) by the sea, abrasional, accumulative, and abrasional-accumulative shores.
Factors other than wave processes also play a role in the formation of seashore; when they predominate, particular types of shores are created—delta shores are formed at the mouths of large rivers, reef-building organisms create coral shores on the coasts of tropical seas, and thermoabrasional shores are formed on the coasts of polar seas under the thermal influence of seawater on frozen rock. Specific features of seashores are imparted by tidal ebb and flow and wind-driven phenomena (coasts with tidal or wind reclamation) and coastal flora (phytogenic-mangrove and reed shores). Physical-geographical zonality is displayed in the formation and distribution of the types of shore— thermoabrasional shores belong to the polar zone; coral and mangrove shores, to the tropical and equatorial zones; and so on. Modern tectonic movement also influences the shaping of seashores. In tectonically sinking regions of a coast, late Ice Age transgression extends further into the heart of the land than in elevated regions. In the general case, all other factors being equal, the submerging of a coast facilitates the abrasion of the shore, and elevation facilitates accumulative processes. When there is a shortage of accretion, on the other hand, elevating sections are subject to abrasion. When there is a surplus incidence of accretion (for example, when there is abundant solid river discharge), accumulative shores form in submerging sections.
A major factor in the development of the shores of water currents is the channel current (for example, in the case of rivers).
Fluvial shore. The activity of the channel current is displayed in the forms of erosion of the shore on the one hand and the accumulation of river drill in particular sections of the channel on the other. The nature of erosion and aggradation of the shores of water currents is determined by the distinctive features of the morphology and dynamics of their channels (meandering, branching, or shifting of sandbanks), their geological structure, and modern tectonic movements. A large role in processes of disintegration of fluvial shores is played by gravitational processes (earth slides, cave-ins, or scree). A distinction is made between flooded (living floodplain) and unflooded (bedrock, terraced) river shores.
The study of shores and their formative processes has great scientific and practical importance. The analysis of modern coastal forms and processes makes it possible to form well-grounded notions about the paleogeography of ancient water basins and rivers. The confinement of seashores to the zero hypsometric level makes it possible to utilize data on shores in studies of the direction and intensity of neotectonic movements of the earth’s crust. Establishing the location in terms of height of ancient coastlines of a particular age makes it possible to form a notion of the direction and intensity (that is, the sign and velocity) of neotectonic movements. The study of shores is of great importance in the design and construction of various ports and shore protection works, the laying of coastal means of communication, and the planning and assimilation of recreation areas; it is important for ensuring the safety of navigation and for purposes of defense, as well as in prospecting for minerals.
REFERENCESZenkovich, V. P. Osnovy ucheniia o razvitii morskikh beregov. Moscow, 1962.
Leont’ev, O. K. Osnovy geomorfologii morskikh beregov. Moscow, 1961.
Longinov, V. V. Dinamika beregovoi zony besprilivnykh morei. Moscow, 1963.
Nevesskii, E. N. Protsessy osadkoobrazovaniia v pribrezhnoi zone moria. Moscow, 1967.
Makkaveev, N. I. Ruslo reki i eroziia v ee basseine. Moscow, 1955. Apollov, B. A. Uchenie o rekakh. Moscow, 1963.
O. K. LEONT’EV
What does it mean when you dream about the shore?
The shore is the place where water and land meet. Perhaps the dreamer is experiencing an internal meeting of their emotional needs with their ego and psyche and are integrating these parts of their personality.