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Cycle Of Erosion
The geographic cycle, or cycle of erosion, is an idealized model that explains the development of relief in landscapes. The model starts with the erosion that follows uplift of land above a base level and ends, if conditions allow, in the formation of a peneplain. Landscapes that show evidence of more than one cycle of erosion are termed "polycyclical". The cycle of erosion and some of its associated concepts have, despite their popularity, been a subject of much criticism. Description William Morris Davis, the originator of the model, divided it into stages whose transition is gradual. The model begins with an uplifted or to-be-uplifted landscape. Then Davis defined a ''youthful'' stage where river incision is the dominant process shaping the landscape. During the ''youthful'' stage height, differences between uplands and valley bottoms increase rapidly. The ''youthful'' stage is followed by a ''mature'' stage in which height differences between valley bottoms and uplands are at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Modelling
Scientific modelling is a scientific activity, the aim of which is to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate by referencing it to existing and usually commonly accepted knowledge. It requires selecting and identifying relevant aspects of a situation in the real world and then developing a model to replicate a system with those features. Different types of models may be used for different purposes, such as conceptual models to better understand, operational models to operationalize, mathematical models to quantify, computational models to simulate, and graphical models to visualize the subject. Modelling is an essential and inseparable part of many scientific disciplines, each of which has its own ideas about specific types of modelling. The following was said by John von Neumann. There is also an increasing attention to scientific modelling in fields such as science education, philosophy of science, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperate Climate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout the year and more distinct seasonal changes compared to tropical climates, where such variations are often small and usually only have precipitation changes. In temperate climates, not only do latitudinal positions influence temperature changes, but sea currents, prevailing wind direction, continentality (how large a landmass is) and altitude also shape temperate climates. The Köppen climate classification defines a climate as "temperate" C, when the mean temperature is above but below in the coldest month to account for the persistency of frost. However, other climate classifications set the minimum at . Zones and climates The north temperate zone extends from the Tropic of Cancer (approximately 23.5° north latitude) to the Arctic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage System (geomorphology)
In geomorphology, drainage systems, also known as river systems, are the patterns formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of land, whether a particular region is dominated by hard or soft rocks, and the gradient of the land. Geomorphologists and hydrologists often view streams as part of drainage basins (and sub-basins). This is the topographic region from which a stream receives runoff, throughflow, and its saturated equivalent, groundwater flow. The number, size, and shape of the drainage basins varies and the larger and more detailed the topographic map, the more information is available. Drainage patterns Per the lie of channels, drainage systems can fall into one of several categories, known as drainage patterns. These depend on the topography and geology of the land. All forms of transitions can occur between parallel, dendritic, and trellis patterns. Accordant versus discordant drainage patterns A drai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeolian Processes
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts. The term is derived from the name of the Greek god Aeolus, the keeper of the winds. Definition and setting ''Aeolian processes'' are those processes of erosion, transport, and deposition of sediments that are caused by wind at or near the surface of the earth. Sediment deposits produced by the action of wind and the sedimentary structures characteristic of these deposits are also described as ''aeolian''. Aeolian processes are most important in areas where there is little or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or semi-arid. This includes much of the polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location. Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks, which consequently break in pieces. Although rain seldom occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter, and the resulting fragments and rubble strewn over the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boreal Climate
The subarctic climate (also called subpolar climate, or boreal climate) is a climate with long, cold (often very cold) winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of an ocean, generally at latitudes from 50° to 70°N, poleward of the humid continental climates. Subarctic or boreal climates are the source regions for the cold air that affects temperate latitudes to the south in winter. These climates represent Köppen climate classification ''Dfc'', ''Dwc'', ''Dsc'', ''Dfd'', ''Dwd'' and ''Dsd''. Description This type of climate offers some of the most extreme seasonal temperature variations found on the planet: in winter, temperatures can drop to below and in summer, the temperature may exceed . However, the summers are short; no more than three months of the year (but at least one month) must have a 24-hour average temperature of at least to fall into this category of climate, and the coldest month should ave ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maritime Climate
An oceanic climate, also known as a marine climate, is the humid temperate climate sub-type in Köppen classification ''Cfb'', typical of west coasts in higher middle latitudes of continents, generally featuring cool summers and mild winters (for their latitude), with a relatively narrow annual temperature range and few extremes of temperature. Oceanic climates can be found in both hemispheres generally between 45 and 63 latitude, most notably in northwestern Europe, northwestern America, as well as New Zealand. Precipitation Locations with oceanic climates tend to feature frequent cloudy conditions with precipitation, low hanging clouds, and frequent fronts and storms. Thunderstorms are normally few, since strong daytime heating and hot and cold air masses meet infrequently in the region. In most areas with an oceanic climate, precipitation comes in the form of rain for the majority of the year. However, some areas with this climate see some snowfall annually during winter. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periglacial
Periglaciation (adjective: "periglacial", also referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refreezes in ice wedges and other structures. "Periglacial" suggests an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes outside areas of past glaciation. Therefore, periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner. Tundra is a common ecological community in periglacial areas. History Periglaciation became a distinct subject within the study of geology after Walery Łoziński, a Polish geologist, introduced the term in 1909. Łoziński drew upon the early work of Johan Gunnar Andersson. According to Alfred Jahn, his introduction of his work at the 1910 International Geological Congress held in Stockholm caused significant discussion. In the field trip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karst
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes. However, in regions where the dissolved bedrock is covered (perhaps by debris) or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and can be totally missing above ground. The study of ''paleokarst'' (buried karst in the stratigraphic column) is important in petroleum geology because as much as 50% of the world's hydrocarbon reserves are hosted in carbonate rock, and much of this is found in porous karst systems. Etymology The English word ''karst'' was borrowed from German in the late 19th century, which entered German much earlier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coastal
The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor important ecosystems such as freshwater or estuarine wetlands, which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor saltmarshes, mangroves or seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals (e.g. mussels, starfish, barnacles) and various kinds of seaweeds. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of . According to a United Nations atlas, 44% of all people live within 5 km (3.3mi) of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The Last Glacial Period ended about 15,000 years ago. The Holocene is the current interglacial. A time with no glaciers on Earth is considered a greenhouse climate state. Quaternary Period Within the Quaternary, which started about 2.6 million years before present, there have been a number of glacials and interglacials. At least eight glacial cycles have occurred in the last 740,000 years alone. Penultimate Glacial Period The Penultimate Glacial Period (PGP) is the glacial period that occurred before the Last Glacial Period. It began about 194,000 years ago and ended 135,000 years ago, with the beginning of the Eemian interglacial. Last Glacial Period The last glacial period was the most recent glacial period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropical Rainforest Climate
A tropical rainforest climate, humid tropical climate or equatorial climate is a tropical climate sub-type usually found within 10 to 15 degrees latitude of the equator. There are some other areas at higher latitudes, such as the coast of southeast Florida, USA, and Okinawa, Japan that fall into the tropical rainforest climate category. They experience high mean annual temperatures, small temperature ranges, and rain that falls throughout the year. Regions with this climate are typically designated ''Af'' by the Köppen climate classification. A tropical rainforest climate is typically hot, very humid, and wet. Description Tropical rain forests have a type of tropical climate in which there is no dry season—all months have an average precipitation value of at least . There are no distinct wet or dry seasons as rainfall is high throughout the months. One day in a tropical rainforest climate can be very similar to the next, while the change in temperature between day and night ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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