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History Of The Wheel In Africa
The wheel in Africa was used, to various extents, throughout the history of Africa. While it may have been common for Africans to manually carry their goods or use pack animals to transport economic goods in Africa, there was broad awareness, knowledge, and use of wheeled transports (e.g., carts, carriages, chariots, wagons) in Africa. However, the environment in some parts of tropical Africa, as well as alternative forms of travel and transport, such as via canoe and beasts of burden/ riding animals (e.g., donkeys, horses, camels), may have resulted in decreased use of animal-drawn wheeled transport in Africa. The wheel was also given other technical applications in Africa, such as a water wheel and a potter's wheel. Environment While the wheel and animal-drawn wheeled transports were usable in the arid environment of the ancient Sahara, and usable in the sparsely wooded, level, arid environment of the ancient Sahel, the environment of the ancient Sudan may have made it rather ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Africa
The history of Africa begins with the emergence of hominids, archaic humans and — around 300–250,000 years ago—anatomically modern humans (''Homo sapiens''), in East Africa, and continues unbroken into the present as a patchwork of diverse and politically developing nation states. The earliest known recorded history arose in Ancient Egypt, and later in Nubia, the Sahel, the Maghreb, and the Horn of Africa. Following the desertification of the Sahara, North African history became entwined with the Middle East and Southern Europe while the Bantu expansion swept from modern day Cameroon (Central Africa) across much of the sub-Saharan continent in waves between around 1000 BC and 1 AD, creating a linguistic commonality across much of the central and Southern continent. During the Middle Ages, Islam spread west from Arabia to Egypt, crossing the Maghreb and the Sahel. Some notable pre-colonial states and societies in Africa include the Ajuran Empire, Bachwezi Em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wheel
A wheel is a circular component that is intended to rotate on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machines. Wheels, in conjunction with axles, allow heavy objects to be moved easily facilitating movement or transportation while supporting a load, or performing labor in machines. Wheels are also used for other purposes, such as a ship's wheel, steering wheel, potter's wheel, and flywheel. Common examples are found in transport applications. A wheel reduces friction by facilitating motion by rolling together with the use of Axle, axles. In order for wheels to rotate, a Moment (physics), moment needs to be applied to the wheel about its axis, either by way of gravity or by the application of another external force or torque. Using the wheel, Sumer, Sumerians invented a device that spins clay as a potter shapes it into the desired object. Terminology The English word '':wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aridification
Aridification is the process of a region becoming increasingly arid, or dry. It refers to long term change, rather than seasonal variation. It is often measured as the reduction of average soil moisture content. It can be caused by reduced precipitation, increased evaporation, lowering of water tables, and changes in ground cover acting individually or in combination. Its major consequences include reduced agricultural production, soil degradation, ecosystem changes and decreased water catchment runoff. Some researchers have found that the Colorado River basin and other parts of western North America are currently undergoing aridification. See also * Arid * Arid Forest Research Institute * Desert * Global warming * Groundwater * Soil moisture * Water balance * Water content * Water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tsetse Fly
Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glossinidae. The tsetse are obligate parasites, which live by feeding on the blood of vertebrate animals. Tsetse have been extensively studied, because of their role in transmitting disease. They have a prominent economic impact in sub-Saharan Africa, as the biological vectors of trypanosomes, causing human and animal trypanosomiasis. Tsetse are multivoltine and long-lived, typically producing about four broods per year, with up to 31 broods over their lifespans. Tsetse can be distinguished from other large flies by two easily-observed features: Primarily, tsetse fold their wings over their abdomens completely when they are resting (so that one wing rests directly on top of the other); Secondly, tsetse also have a long proboscis, extending d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals who are raised for consumption, and sometimes used to refer solely to farmed ruminants, such as cattle, sheep, goats and pigs. Horses are considered livestock in the United States. The USDA classifies pork, veal, beef, and lamb (mutton) as livestock, and all livestock as red meat. Poultry and fish are not included in the category. The breeding, maintenance, slaughter and general subjugation of livestock, called '' animal husbandry'', is a part of modern agriculture and has been practiced in many cultures since humanity's transition to farming from hunter-gatherer lifestyles. Animal husbandry practices have varied widely across cultures and time periods. It continues to play a major economic and cultural role in numerous communities. Lives ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tse-tse Fly
Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glossinidae. The tsetse are obligate parasites, which live by feeding on the blood of vertebrate animals. Tsetse have been extensively studied, because of their role in transmitting disease. They have a prominent economic impact in sub-Saharan Africa, as the biological vectors of trypanosomes, causing human and animal trypanosomiasis. Tsetse are multivoltine and long-lived, typically producing about four broods per year, with up to 31 broods over their lifespans. Tsetse can be distinguished from other large flies by two easily-observed features: Primarily, tsetse fold their wings over their abdomens completely when they are resting (so that one wing rests directly on top of the other); Secondly, tsetse also have a long proboscis, extending di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paved Road
A road surface (British English), or pavement (American English), is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, hoggin, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled (hard-surfaced) and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways. Pavements are crucial to countries such as United States and Canada, which heavily depend on road tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sudan (region)
Sudan is the geographical region to the south of the Sahara, stretching from Western Africa to Central and Eastern Africa. The name derives from the Arabic ' (), or "the lands of the Blacks", referring to West Africa and northern Central Africa. Historically, the name was understood to denote the western part of the Sahel region. It thus roughly encompassed the geographical belt between the Sahara and the coastal West Africa. In modern usage, the term "Sudan" is also used in a separate context to refer specifically to the geographic region comprising the present-day countries of the Sudan, including its western region which forms a part of the country, and South Sudan, which gained its independence in 2011. In order to avoid confusion, the term "the Sudans" has become the preferred option when describing this region. Geography Sudan is marked by hay, forest cliffs and gallery forests along the rivers. Drought and livestock grazing threaten the area with desertification. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahel
The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid climate, it stretches across the south-central latitudes of Northern Africa between the Atlantic Ocean and the Red Sea. The Sahel part of Africa includes – from west to east – parts of northern Senegal, southern Mauritania, central Mali, northern Burkina Faso, the extreme south of Algeria, Niger, the extreme north of Nigeria, Cameroon and Central African Republic, central Chad, central and southern Sudan, the extreme north of South Sudan, Eritrea and Ethiopia. Historically, the western part of the Sahel was sometimes known as the Sudan region (''bilād as-sūdān'' "lands of the Sudan"). This belt was located between the Sahara and the coastal areas of West Africa. There are frequent shortages of food and water due to the dry h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahara
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History Of Africa
The history of Africa begins with the emergence of hominids, archaic humans and — around 300–250,000 years ago—anatomically modern humans (''Homo sapiens''), in East Africa, and continues unbroken into the present as a patchwork of diverse and politically developing nation states. The earliest known recorded history arose in Ancient Egypt, and later in Nubia, the Sahel, the Maghreb, and the Horn of Africa. Following the desertification of the Sahara, North African history became entwined with the Middle East and Southern Europe while the Bantu expansion swept from modern day Cameroon (Central Africa) across much of the sub-Saharan continent in waves between around 1000 BC and 1 AD, creating a linguistic commonality across much of the central and Southern continent. During the Middle Ages, Islam spread west from Arabia to Egypt, crossing the Maghreb and the Sahel. Some notable pre-colonial states and societies in Africa include the Ajuran Empire, Bachwezi Em ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most arid climates straddle the Equator; these regions include parts of Africa, Asia, South America, North America, and Australia. Change over time The distribution of aridity at any time is largely the result of the general circulation of the atmosphere. The latter does change significantly over time through climate change. For example, temperature increase by 1.5–2.1 percent across the Nile Basin over the next 30–40 years could change the region from semi-arid to arid, significantly reducing the land usable for agriculture. In addition, changes in land use can increase demands on soil water and thereby increase aridity. See also * Arid Forest Research Institute * Aridity index * Desert climate * Desiccation tolerance * Drought * Hu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
