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Ma'adin Ijafen
Ma'adin Ijafen is an archaeological site in an area of dunes in the Sahara in eastern Mauritania. It was first discovered in the early 1960s by the French explorer Théodore Monod. Monod followed up on information provided by local hunters, searching for evidence to confirm the magnitude of the historical trans-Saharan copper trade. into the desert, he located bundles of cowrie shells and ingots of brass wrapped in ropes and matting and hidden in the sand. The site was originally thought to be the site of a caravan wreck, but Monod believed that the valuables had been hidden intentionally, either by the travelers seeking to prevent a bandit attack or by bandits hoping to retrieve the items later. It is unclear where the caravan originated from, or what prevented the treasure from being retrieved. Analysis All told, Monod recovered 2,085 brass ingots of approximately in length, weighing up to each. They were tied up in bundles of 100 ingots each. He believed that each came ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called ''Erg (landform), ergs'' or ''sand seas''. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the wiktionary:stoss, stoss (upflow) side, where the sand is pushed up the dune, and have a shorter ''slip face'' in the lee side. The valley or trough between dunes is called a ''dune slack''. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation that would otherwise interfere with the development of dunes. However, sand deposits are not restricted to deserts, and dunes are also found along sea shores, along streams in semiarid climates, in areas of Outwash plain, glacial outwash ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ingot
An ingot is a piece of relatively pure material, usually metal, that is Casting, cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products. Ingots usually require a second procedure of shaping, such as cold/hot working, cutting, or milling to produce a useful final product. Non-metallic and semiconductor materials prepared in bulk form may also be referred to as ingots, particularly when cast by mold based methods. Precious metal ingots can be used as currency (with or without being processed into other shapes), or as a currency reserve, as with gold bars. Types Ingots are generally made of metal, either pure or alloy, heated past its melting point and cast into a bar or block using a mold chill method. A special case are polycrystalline or single crystal ingots made by pulling from a molten melt. Single crystal Single crystal ingots (called boule (crystal), boules) of materials are grown (crystal growth) using ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maldives
The Maldives, officially the Republic of Maldives, and historically known as the Maldive Islands, is an Archipelagic state, archipelagic country in South Asia located in the Indian Ocean. The Maldives is southwest of Sri Lanka and India, about from the Asian continent's mainland. The Maldives' chain of Atolls of the Maldives, 26 atolls stretches across the equator from Atolls of the Maldives#Ihavandhippolhu, Ihavandhippolhu Atoll in the north to Addu Atoll in the south. The Maldives is the smallest List of sovereign states and dependent territories in Asia, country in Asia. Its land area is only , but this is spread over roughly of the sea, making it one of the world's most spatially dispersed sovereign states. With a population of 515,132 in the 2022 census, it is the second List of Asian countries by population, least populous country in Asia and the List of countries and dependencies by area, ninth-smallest country by area, but also one of the List of countries and depend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northwestern Europe
Northwestern Europe, or Northwest Europe, is a loosely defined subregion of Europe, overlapping Northern and Western Europe. The term is used in geographic, history, and military contexts. Geographic definitions Geographically, Northwestern Europe is given by some sources as a region which includes Great Britain, Ireland, Belgium, the Netherlands, Luxembourg, Northern France, parts of or all of Germany, Denmark, Norway, Sweden, and Iceland. In some works, Switzerland, Finland, and Austria are also included as part of Northwestern Europe. Under the Interreg program, funded by the European Regional Development Fund, "North-West Europe" (NWE) is a region of European Territorial Cooperation that includes Belgium, Ireland, Luxembourg, Switzerland, the Netherlands and parts of France and Germany. Ethnography During the Reformation, some parts of Northwestern Europe converted to Protestantism, in a manner which differentiated the region from its Roman Catholic neighbors elsewhe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotope Geochemistry
Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various Chemical element, elements. Variations in isotopic abundance are measured by isotope-ratio mass spectrometry, and can reveal information about the ages and origins of rock, air or water bodies, or processes of mixing between them. Stable isotope geochemistry is largely concerned with isotopic variations arising from mass-dependent isotope fractionation, whereas radiogenic isotope geochemistry is concerned with the products of natural radioactivity. Stable isotope geochemistry For most stable isotopes, the magnitude of fractionation from kinetic fractionation, kinetic and equilibrium fractionation is very small; for this reason, enrichments are typically reported in "per mil" (Per mille, ‰, parts per thousand). These enrichments (δ) represent the ratio of heavy isotope to light isotope in the sample over the ratio of a Reference Materials fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Era
Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the original Anno Domini (AD) and Before Christ (BC) notations used for the same calendar era. The two notation systems are numerically equivalent: " CE" and "AD " each describe the current year; "400 BCE" and "400 BC" are the same year. The expression can be traced back to 1615, when it first appears in a book by Johannes Kepler as the (), and to 1635 in English as " Vulgar Era". The term "Common Era" can be found in English as early as 1708, and became more widely used in the mid-19th century by Jewish religious scholars. Since the late 20th century, BCE and CE have become popular in academic and scientific publications on the grounds that BCE and CE are religiously neutral terms. They have been promoted as more sensitive to non-Christia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monetaria Annulus 0009
''Monetaria'' is a genus of sea snails, marine gastropod mollusks in the family Cypraeidae, the cowries. Taxonomy The generic placement is based on the molecular work of Meyer (2003). Some authors have previously placed species in the genus ''Erosaria'' (e.g. caputserpentis, by Lorenz and Hubert, 2000) Species Species within the genus ''Monetaria'' include: * '' Monetaria annulus'' (Linnaeus, 1758) *'' Monetaria caputdraconis'' ( Melvill, 1888) * '' Monetaria caputophidii'' (Schilder, 1927) * ''Monetaria caputserpentis'' (Linnaeus, 1758) * ''Monetaria moneta'' (Linnaeus, 1758) * '' Monetaria obvelata'' (Lamarck, 1810) * † '' Monetaria simplicissima'' (K. Martin, 1899) ;Species brought into synonymy : * ''Monetaria britannica'' Schilder, 1927: synonym of ''Monetaria moneta'' (Linnaeus, 1758) * ''Monetaria camelorum'' (Rochebrune, 1884): synonym of ''Monetaria annulus'' (Linnaeus, 1758) * ''Monetaria candidata'' Sulliotti, 1924: synonym of ''Monetaria caputserpentis'' (Linna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camel Train
A camel train, caravan, or camel string is a series of camels carrying passengers and goods on a regular or semi-regular service between points. Despite rarely travelling faster than human walking speed, for centuries camels' ability to withstand harsh conditions made them ideal for communication and trade in the desert areas of North Africa and the Arabian Peninsula. Camel trains were also used sparingly elsewhere around the globe. Since the early 20th century they have been largely replaced by motorized vehicles or air traffic. Africa, Asia and the Middle East By far, the greatest use of camel trains occurs between North and West Africa by the Tuareg, Shuwa and Hassaniyya, as well as by culturally-affiliated groups like the Toubou, Hausa and Songhay. These camel trains conduct trade in and around the Sahara Desert and Sahel. Trains travel as far south as central Nigeria and northern Cameroon in the west, and northern Kenya in the east of the continent. In antiquity, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cowrie Shells
Cowrie or cowry () is the common name for a group of small to large sea snails in the family Cypraeidae. Cowrie shells have held cultural, economic, and ornamental significance in various cultures. The cowrie was the shell most widely used worldwide as shell money. It is most abundant in the Indian Ocean, and was collected in the Maldive Islands, in Sri Lanka, along the Indian Malabar coast, in Borneo and on other East Indian islands, in Maluku in the Pacific, and in various parts of the African coast from Ras Hafun, in Somalia, to Mozambique. Cowrie shell money was important in the trade networks of Africa, South Asia, and East Asia. In the United States and Mexico, cowrie species inhabit the waters off Central California to Baja California (the chestnut cowrie is the only cowrie species native to the eastern Pacific Ocean off the coast of the United States; further south, off the coast of Mexico, Central America and Peru, Little Deer Cowrie habitat can be found; and furt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sahara
The Sahara (, ) is a desert spanning across North Africa. With an area of , it is the largest hot desert in the world and the list of deserts by area, third-largest desert overall, smaller only than the deserts of Antarctica and the northern Arctic. The name "Sahara" is derived from , a broken plural form of ( ), meaning "desert". The desert covers much of North Africa, excluding the fertile region on the Mediterranean Sea coast, the Atlas Mountains of the Maghreb, and the Nile, Nile Valley in Egypt and the Sudan. It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south it is bounded by the Sahel, a belt of Tropical and subtropical grasslands, savannas, and shrublands, semi-arid tropical savanna around the Niger River valley and the Sudan (region), Sudan region of sub-Saharan Africa. The Sahara can be divided into several regions, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable, unalloyed metallic form. This means that copper is a native metal. This led to very early human use in several regions, from . Thousands of years later, it was the first metal to be smelted from sulfide ores, ; the first metal to be cast into a shape in a mold, ; and the first metal to be purposely alloyed with another metal, tin, to create bronze, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
