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Peneplain
In geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or penultimate) stage of fluvial erosion during times of extended tectonic stability. Peneplains are sometimes associated with the cycle of erosion theory of William Morris Davis, but Davis and other researchers have also used the term in a purely descriptive manner without any theory or particular genesis attached. Discussion 390px, Sketch of a hypothetical peneplain formation after an orogeny. The existence of some peneplains, and peneplanation as a process in nature, is not without controversy, due to a lack of contemporary examples and uncertainty in identifying relic examples. By some definitions, peneplains grade down to a base level represented by sea level, yet in other definitions such a condition is ignored. Geomorphologist K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pediplain
In geology and geomorphology a pediplain (from the Latin ''pes'', genitive case ''pedis'', meaning "foot") is an extensive plain formed by the coalescence of pediment (geology), pediments. The processes through which pediplains forms is known as pediplanation. The concepts of pediplain and pediplanation were first developed by geologist Lester Charles King in his 1942 book ''South African Scenery''. The concept gained notoriety as it was juxtaposed to peneplain, peneplanation. The coalesced pediments of the pediplains may form a series of very gentle concave slopes. Pediplains main difference to William Morris Davis, W. M. Davis’ peneplains is in the history and processes behind, and less so in the final shape. Perhaps the most notable difference in form that may be present is that of residual hills which in Davis’ peneplains are to have gentle slopes while in pediplains they ought to have the same steepness as the slopes in the early stages of erosion leading to pediplanati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 similar to the human life i.e. Youth Stage, Mature Stage and Old Stage. The model begins with an uplifted sate of landscape. Then Davis defined a ''youthful'' stage where river incision or vertical erosion 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 ''ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sub-Mesozoic Hilly Peneplains
300px, An undulating hilly landscape in Falkenberg Municipality, Halland. file:Dagsås_-_KMB_-_16000700002822.jpg">300px, An undulating hilly landscape in Halland.html" ;"title="Varberg Municipality, Halland">Varberg Municipality, Halland. The Sub-Mesozoic hilly peneplains or Sub-Mesozoic hilly relief is a landscape in Scandinavia made up of undulating hills and joint valleys and occasional kaolinized bedrock in valley bottoms. The landscape formed in the Mesozoic Era and was eventually drowned by the sea during the Campanian transgression and covered by a thick blanket of Cretaceous sedimentary rocks. Later erosion of the cover rocks partly re-exposed this landscape. During the Quaternary epoch the re-exposed Mesozoic hilly relief escaped major glacier erosion being only surficially scoured in parts. The Sub-Mesozoic hilly relief formed starting from a peneplain formed in the Permian and Triassic. Remnants of this peneplain can be traced as a tilted summit accordance in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plain
In geography, a plain, commonly known as flatland, is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or Highland, uplands. Plains are one of the major landforms on earth, being present on all continents and covering more than one-third of the world's land area. Plains in many areas are important for agriculture. There are various types of plains and biomes on them. Description A plain or flatland is a flat expanse of land with a layer of grass that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or Highland, uplands. Plains are one of the major landforms on earth, where they are present on all continents, and cover more than one-third of the world's land area. In a valley, a plain is enclosed on tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Level
In geology and geomorphology a base level is the lower limit for the vertical position of an erosion, erosion process. The modern term was introduced by John Wesley Powell in 1875. The term was subsequently appropriated by William Morris Davis who used it in his cycle of erosion theory. The "ultimate base level" is the surface that results from horizontal projection of the sea level under landmasses (the geoid). It is to this base level that topography tends to approach due to erosion, eventually forming a peneplain close to the end of a cycle of erosion.Phillips, Jonathan D. (2002)"Erosion, isostatic response, and the missing peneplains" ''Geomorphology (journal), Geomorphology'', Vol. 45, No. 3-4Elsevier, 15 June 2002, pp. 225-241. . There are also lesser structural geology, structural base levels where erosion is delayed by resistant rocks. Examples of this include karst regions underlain by insoluble rock. Base levels may be local when large landmasses are far from the sea or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenees
The Pyrenees are a mountain range straddling the border of France and Spain. They extend nearly from their union with the Cantabrian Mountains to Cap de Creus on the Mediterranean coast, reaching a maximum elevation of at the peak of Aneto. For the most part, the main crest forms a divide between Spain and France, with the microstate of Andorra sandwiched in between. Historically, the Crown of Aragon and the Kingdom of Navarre extended on both sides of the mountain range. Etymology In Greek mythology, Pyrene is a princess who gave her name to the Pyrenees. The Greek historian Herodotus says Pyrene is the name of a town in Celtic Europe. According to Silius Italicus, she was the virgin daughter of Bebryx, a king in Mediterranean Gaul by whom the hero Hercules was given hospitality during his quest to steal the cattle of Geryon during his famous Labours. Hercules, characteristically drunk and lustful, violates the sacred code of hospitality and rapes his host's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tibetan Plateau
The Tibetan Plateau, also known as the Qinghai–Tibet Plateau or Qingzang Plateau, is a vast elevated plateau located at the intersection of Central Asia, Central, South Asia, South, and East Asia. Geographically, it is located to the north of Himalayas and the Indian subcontinent, and to the south of Tarim Basin and Mongolian Plateau. Geopolitically, it covers most of the Tibet Autonomous Region, most of Qinghai, western half of Sichuan, Southern Gansu provinces, southern Xinjiang province in Western China, Bhutan, the Administrative divisions of India, Indian regions of Ladakh and Lahaul and Spiti district, Lahaul and Spiti (Himachal Pradesh) as well as Gilgit-Baltistan in Pakistan, northwestern Nepal, eastern Tajikistan and southern Kyrgyzstan. It stretches approximately north to south and east to west. It is the world's highest and largest plateau above sea level, with an area of . With an average elevation exceeding and being surrounded by imposing mountain ranges that har ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planation Surface
In geology and geomorphology a planation surface is a large-scale land surface that is almost flat with the possible exception of some residual hills. The processes that form planation surfaces are labelled collectively planation and are exogenic (chiefly erosion). Planation surfaces are planated regardless of bedrock structures. On Earth, they constitute some of the most common landscapes. Geological maps indicate that planation surfaces may comprise 65% of the landscapes on Saturn's largest moon, Titan, which hosts a hydrological cycle of liquid methane. Peneplains and pediplains are types of planation surfaces planated respectively by "peneplanation" and "pediplanation". In addition to these there are planation surfaces proposed to be formed by cryoplanation, marine processes, areal glacial erosion and salt weathering. The term ''planation surface'' is often preferred over others because some more specific planation surface types and processes remain controversial. Etchp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, transports it to another location where it is deposit (geology), deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by Solvation, dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and Wind wave, waves; glacier, glacial Plucking (glaciation), plucking, Abrasion (geology), abrasion, and scour; areal flooding; Aeolian processes, wind abrasion; groundwater processes; and Mass wastin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Morris Davis
William Morris Davis (February 12, 1850 – February 5, 1934) was an American geographer, geologist, geomorphologist, and meteorologist, often called the "father of American geography". He was born into a prominent Quaker family in Philadelphia, Pennsylvania, son of Edward M. Davis and Maria Mott Davis (a daughter of the women's advocate Lucretia Mott). Davis studied geology and geography at Harvard's Lawrence Scientific School and then joined the Harvard sponsored geographic exploration party to the Colorado territory, led by the inaugural Sturgis-Hooper professor of geology, Josiah Dwight Whitney. Wild stories had circulated since soon after the Louisiana Purchase about Rocky Mountains peaks 18,000 feet or higher. The Harvard expedition set out to investigate, and found none, but they did find "14ers" (14,000-plus feet). He graduated from Harvard University in 1869 and received a Master of Mining Engineering in the following year. Davis worked for Nathaniel Shaler as a fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
