Desertification is a type of gradual land degradation of fertile land into arid desert due to a combination of natural processes and human activities.
Erosion is the action of surface processes that removes soil,rock,or dissolved material from one location on the Earth's crust and then transports it to another location where it is 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 dissolution. Eroded sediment or solutes may be transported just a few millimetres,or for thousands of kilometres.
A monsoon is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscillation of the Intertropical Convergence Zone (ITCZ) between its limits to the north and south of the equator. Usually,the term monsoon is used to refer to the rainy phase of a seasonally changing pattern,although technically there is also a dry phase. The term is also sometimes used to describe locally heavy but short-term rains.
Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents,that is,water,ice (glaciers),snow,air (wind),plants,and animals. In accordance with these agents,erosion is sometimes divided into water erosion,glacial erosion,snow erosion,wind (aeolian) erosion,zoogenic erosion and anthropogenic erosion such as tillage erosion. Soil erosion may be a slow process that continues relatively unnoticed,or it may occur at an alarming rate causing a serious loss of topsoil. The loss of soil from farmland may be reflected in reduced crop production potential,lower surface water quality and damaged drainage networks. Soil erosion could also cause sinkholes.
Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and,through the processes of weathering and erosion,is broken down and subsequently transported by the action of wind,water,or ice or by the force of gravity acting on the particles. For example,sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation;if buried,they may eventually become sandstone and siltstone through lithification.
A dust storm,also called a sandstorm,is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Fine particles are transported by saltation and suspension,a process that moves soil from one place and deposits it in another.
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil or as sediment mixed in suspension with water. Silt usually has a floury feel when dry,and lacks plasticity when wet. Silt can also be felt by the tongue as granular when placed on the front teeth.
Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded. They are characterized by steep slopes,minimal vegetation,lack of a substantial regolith,and high drainage density. Ravines,gullies,buttes,hoodoos and other such geologic forms are common in badlands.
A loess is a clastic,predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loesses or similar deposits.
The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of central North America,extending along the east flank of the Rocky Mountains from the Gulf Coast region to the Arctic Beaufort Sea. In Canada,it encompasses the Canadian Prairies separating the Canadian Rockies from the Canadian Shield,as well as the Boreal Plains and Taiga Plains east of the Mackenzie and Richardson Mountains;while in the United States,it includes the Great Plains of the West/Midwest and the tallgrass prairie region to the south of the Great Lakes extending east to the Appalachian Plateau region.
The Tibetan Plateau,also known as Qinghai–Tibet Plateau and Qing–Zang Plateau,is a vast elevated plateau located at the intersection of Central,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 in Western China,southern Xinjiang,Bhutan,the Indian regions of Ladakh and Lahaul and Spiti as well as Gilgit-Baltistan in Pakistan,northwestern Nepal,eastern Tajikistan and southern Kyrgyzstan. It stretches approximately 1,000 kilometres (620 mi) north to south and 2,500 kilometres (1,600 mi) east to west. It is the world's highest and largest plateau above sea level,with an area of 2,500,000 square kilometres (970,000 sq mi). With an average elevation exceeding 4,500 metres (14,800 ft) and being surrounded by imposing mountain ranges that harbor the world's two highest summits,Mount Everest and K2,the Tibetan Plateau is often referred to as "the Roof of the World".
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. 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 Hexi Corridor,also known as the Gansu Corridor,is an important historical region located in the modern western Gansu province of China. It refers to a narrow stretch of traversable and relatively arable plain west of the Yellow River's Ordos Loop,flanked between the much more elevated and inhospitable terrains of the Mongolian and Tibetan Plateaus.
Mineral dust is atmospheric aerosol originated from the suspension of minerals constituting the soil,composed of various oxides and carbonates. Human activities lead to 25% of the airborne dust (particulates) load in the atmosphere. The Sahara Desert is the major source of mineral dust,which subsequently spreads across the Mediterranean and Caribbean seas into northern South America,Central America,and eastern North America,and Europe. Additionally,it plays a significant role in the nutrient inflow to the Amazon rainforest. The Gobi Desert is another source of dust in the atmosphere,which affects eastern Asia and western North America.
The Great Green Wall,officially known as the Three-North Shelter Forest Program,also known as the Three-North Shelterbelt Program,is a series of human-planted windbreaking forest strips (shelterbelts) in China,designed to hold back the expansion of the Gobi Desert,and provide timber to the local population. The program started in 1978,and is planned to be completed around 2050,at which point it will be 4,500 kilometres (2,800 mi) long.
Aeolian landforms,or Eolian landforms,are produced by either the erosive or depositive action of wind. These features may be built up from sand or snow,or eroded into rock,snow,or ice.
A desert is a landscape where little precipitation occurs and,consequently,living conditions create unique biomes and ecosystems. 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.
Paha are elongated landforms composed either of only loess or till capped by loess. In Iowa,paha are prominent hills that are oriented from northwest to southeast,formed during the period of mass erosion that developed the Iowan surface,and they are considered erosional remnants since they often preserve buried soils. Paha generally rise above the surrounding landscape more than 6.1 metres (20 ft). The word paha means hill in Dakota Sioux. Well known pahas include the hill on which the town of Mount Vernon,Iowa developed,Casey's Paha in Tama County,Iowa,and the Kirkwood Paha,home of Kirkwood Community College's campus. These features are found in other regions of the United States and in Europe,where they are known as greda.
The Gobi Desert is a large,cold desert and grassland region located in northern China and southern Mongolia. It is the sixth largest desert in the world. The name of the desert comes from the Mongolian word gobi,used to refer to all of the waterless regions in the Mongolian Plateau;in Chinese,gobi is used to refer to rocky,semi-deserts such as the Gobi itself rather than sandy deserts.
The Mu Us Desert,also known as the Maowusu Desert,is a desert in the northern Ordos Plateau in Inner Mongolia,Northwest China. Its southeastern end is crossed by the Ming Great Wall,and it forms the southern portion of the Ordos Desert. The Wuding River drains the area,and then flows into the Ordos Loop of the Yellow River.
