|
Vertisols
A vertisol is a Soil Order in the USDA soil taxonomy and a Reference Soil Group in the World Reference Base for Soil Resources (WRB). It is also defined in many other soil classification systems. In the Australian Soil Classification it is called vertosol. The natural vegetation of vertisols is grassland, savanna, or grassy woodland. The heavy texture and unstable behaviour of the soil makes it difficult for many tree species to grow, and forest is uncommon. Composition Vertisols have a high content of expansive clay minerals (many of them belonging to the montmorillonites) that form deep cracks in drier seasons or years. In a phenomenon known as argillipedoturbation, alternate shrinking and swelling causes ''self-ploughing'', where the soil material consistently mixes itself, causing some vertisols to have an extremely deep A horizon and no B horizon. (A soil with no B horizon is called an ''A/C soil''). This heaving of the underlying material to the surface often creat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argillipedoturbation
Argillipedoturbation, sometimes referred to as self-mulching, is a process of soil mixing caused by the shrinking and swelling of the smectite clays contained in soil. It is an effect specific to soils of the vertisolic variety, and is triggered by the constant cycles of wetting and drying. It is characterized by wide (up to ), deep ( or more) vertical cracks in the solum that contain differing materials from the rest of the soil layer they are found in, as well as sloughed-in surface materials. In order for argillipedoturbation to occur, the soil must be at least 30% clay content. The expression of argillipedoturbation depends to a large degree on the exact clay content of the soil, as well as on what other minerals make up the soil composition. Argillipedoturbation can be strong enough that it can affect the soil horizons by combining the different horizons, making them difficult to distinguish. It can also result in a gently-rolling surface referred to as gilgai A gilgai is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Reference Base For Soil Resources
The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. It is edited by a working group of the International Union of Soil Sciences (IUSS). WRB, 4th edition (2022) Background History Since the 19th century, several countries developed national soil classification systems. During the 20th century, the need for an international soil classification system became more and more obvious. From 1971 to 1981, the Food and Agriculture Organization (FAO) and UNESCO published the Soil Map of the World, 10 volumes, scale 1 : 5 M). The Legend for this map, published in 1974 under the leadership of Rudi Dudal, became the FAO soil classification. Many ideas from national soil classification systems were brought together in this worldwide-applicable system, among them the idea of diagnostic horizons as established in the '7th approximation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gilgai
A gilgai is a small, ephemeral lake formed from a surface depression in expanding clay soils. Gilgai is also used to refer to the overall micro-relief in such areas, consisting of mounds and depressions. The name comes from an Australian Aboriginal word meaning small water hole. The pools are commonly a few metres across and less than deep but, in some instances, they may be several metres deep and up to across. Gilgais are found worldwide wherever there are cracking clay soils and marked wet and dry seasons. Gilgais are also called melonholes, crabholes, hogwallows, or puff and shelf formations. Formation Gilgais are thought to form in vertisols through repeated cycles of swelling when wet and subsequent shrinkage upon drying. That action, known as argillipedoturbation, causes the soil to crack when dry, allowing loose soil material to fill the cracks. When the soil swells upon subsequent re-wetting, the soil pressure cannot be dispersed into the now-full cracks and the so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraná River
The Paraná River ( ; ; ) is a river in south-central South America, running through Brazil, Paraguay, and Argentina for some ."Parana River". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Web. 26 May. 2012 https://www.britannica.com/EBchecked/topic/443063/Parana-River . "Rio de la Plata". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Web. 26 May. 2012 https://www.britannica.com/EBchecked/topic/463804/Rio-de-la-Plata Among South American rivers, it is second in length only to the Amazon River. It merges with the Paraguay River and then farther downstream with the Uruguay River to form the Río de la Plata and empties into the Atlantic Ocean. The first European to go up the Paraná River was the Venetian explorer Sebastian Cabot (explorer), Sebastian Cabot, in 1526, while working for Spain. A drought hit the river in 2021, causing a 77-year low. Etymology In eastern South Amer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chad
Chad, officially the Republic of Chad, is a landlocked country at the crossroads of North Africa, North and Central Africa. It is bordered by Libya to Chad–Libya border, the north, Sudan to Chad–Sudan border, the east, the Central African Republic to Central African Republic–Chad border, the south, Cameroon to Cameroon–Chad border, the southwest, Nigeria to Chad–Nigeria border, the southwest (at Lake Chad), and Niger to Chad–Niger border, the west. Chad has a population of 19 million, of which 1.6 million live in the Capital city, capital and largest city of N'Djamena. With a total area of around , Chad is the fifth-largest country in Africa and the List of countries and dependencies by area, twentieth largest nation by area. Chad has several regions: the Sahara desert in the north, an arid zone in the centre known as the Sahel, and a more fertile Sudanian Savanna zone in the south. Lake Chad, after which the country is named, is the second-largest wetl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kenya
Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. Kenya's capital and largest city is Nairobi. Its second-largest and oldest city is Mombasa, a major port city located on Mombasa Island. Other major cities within the country include Kisumu, Nakuru & Eldoret. Going clockwise, Kenya is bordered by South Sudan to the northwest (though much of that border includes the disputed Ilemi Triangle), Ethiopia to the north, Somalia to the east, the Indian Ocean to the southeast, Tanzania to the southwest, and Lake Victoria and Uganda to the west. Kenya's geography, climate and population vary widely. In western, rift valley counties, the landscape includes cold, snow-capped mountaintops (such as Batian, Nelion and Point Lenana on Mount Kenya) with vast surrounding forests, wildlife and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethiopia
Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Kenya to the south, South Sudan to the west, and Sudan to the northwest. Ethiopia covers a land area of . , it has around 128 million inhabitants, making it the List of countries and dependencies by population, thirteenth-most populous country in the world, the List of African countries by population, second-most populous in Africa after Nigeria, and the most populous landlocked country on Earth. The national capital and largest city, Addis Ababa, lies several kilometres west of the East African Rift that splits the country into the African Plate, African and Somali Plate, Somali tectonic plates. Early modern human, Anatomically modern humans emerged from modern-day Ethiopia and set out for the Near East and elsewhere in the Middle Paleolithi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sudan
Sudan, officially the Republic of the Sudan, is a country in Northeast Africa. It borders the Central African Republic to the southwest, Chad to the west, Libya to the northwest, Egypt to the north, the Red Sea to the east, Eritrea and Ethiopia to the southeast, and South Sudan to the south. Sudan has a population of 50 million people as of 2024 and occupies 1,886,068 square kilometres (728,215 square miles), making it Africa's List of African countries by area, third-largest country by area and the third-largest by area in the Arab League. It was the largest country by area in Africa and the Arab League until the 2011 South Sudanese independence referendum, secession of South Sudan in 2011; since then both titles have been held by Algeria. Sudan's capital and most populous city is Khartoum. The area that is now Sudan witnessed the Khormusan ( 40000–16000 BC), Halfan culture ( 20500–17000 BC), Sebilian ( 13000–10000 BC), Qadan culture ( 15000–5000 BC), the war of Jebel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deccan Plateau
The Deccan is a plateau extending over an area of and occupies the majority of the Indian peninsula. It stretches from the Satpura Range, Satpura and Vindhya Ranges in the north to the northern fringes of Tamil Nadu in the south. It is bound by the mountain ranges of the Western Ghats and the Eastern Ghats on the sides, which separate the region from the Western Coastal Plains, Western and Eastern Coastal Plains respectively. It covers most of the Indian States of Maharashtra, Karnataka, Telangana and Andhra Pradesh excluding the coastal regions, and minor portions of Tamil Nadu and Kerala. The plateau is marked by rocky terrain with an average elevation of about . It is subdivided into Maharashtra Plateau, Karnataka Plateau, and Rayalaseema & Telangana Plateau. The Deccan Traps in the north west were formed by multiple layers of igneous rocks laid down by basaltic lava flows following a massive volcanic eruption that occurred during the end of the Cretaceous period (66 Millio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New South Wales
New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South Australia to the west. Its coast borders the Coral Sea, Coral and Tasman Seas to the east. The Australian Capital Territory and Jervis Bay Territory are Enclave and exclave, enclaves within the state. New South Wales' state capital is Sydney, which is also Australia's most populous city. , the population of New South Wales was over 8.3 million, making it Australia's most populous state. Almost two-thirds of the state's population, 5.3 million, live in the Greater Sydney area. The Colony of New South Wales was founded as a British penal colony in 1788. It originally comprised more than half of the Australian mainland with its Western Australia border, western boundary set at 129th meridian east in 1825. The colony then also includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queensland
Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south, respectively. To the east, Queensland is bordered by the Coral Sea and the Pacific Ocean; to the state's north is the Torres Strait, separating the Australian mainland from Papua New Guinea, and the Gulf of Carpentaria to the north-west. With an area of , Queensland is the world's List of country subdivisions by area, sixth-largest subnational entity; it List of countries and dependencies by area, is larger than all but 16 countries. Due to its size, Queensland's geographical features and climates are diverse, and include tropical rainforests, rivers, coral reefs, mountain ranges and white sandy beaches in its Tropical climate, tropical and Humid subtropical climate, sub-tropical c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
