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Xalnene Tuff Footprints
The Xalnene Tuff footprints are a geological academic controversy, concerning a 2005 discovery of 269 markings in a geological layer in the Valsequillo Basin, south of the city of Puebla, Mexico, which were originally interpreted to be human and animal footprints. The layer was variously dated to 40,000 years Before Present (BP) or 1.3million years BP, both dates significantly before the currently accepted date for the settlement of the Americas. A 2010 study argues that the marks were made by recent mining activities. Past theories The Clovis people were at one time considered to be the first inhabitants of the Americas, migrating into the area 13,100 years BP. However, tools, bone structures, genetics, and languages indicate that the early Americans were from many origins, and there have been some sites dated to 15–16,000 years BP. Methodology Carbon dating techniques were used. Implications of the discovery Implications of the find by González et al. are that other colo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puebla De Los Ángeles
Puebla de Zaragoza (; nah, Cuetlaxcoapan), formally Heroica Puebla de Zaragoza, formerly Puebla de los Ángeles during colonial times, or known in English simply as Puebla, is the seat of Puebla Municipality. It is the capital and largest city of the state of Puebla, and the fourth largest city in Mexico, after Mexico City, Monterrey, and Guadalajara. A viceregal era planned city, it is located in the southern part of Central Mexico on the main route between Mexico City and Mexico's main Atlantic ocean, Atlantic port, Veracruz, Veracruz, Veracruz—about east southeast of Mexico City and about west of Veracruz. The city was founded in 1531 in an area called Cuetlaxcoapan, which means "where serpents change their skin", between two of the main indigenous settlements at the time, Tlaxcala and Cholula (Mesoamerican site), Cholula. This valley was not populated in the 16th century, as in the pre-Columbian, pre-Hispanic period this area was primarily used for the "flower wars" betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Mexico covers ,Mexico ''''. . making it the world's 13th-largest country by are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Before Present
Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale. The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must now account for. In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation RCYBP stands for the explicit "radio carbon years before present". Usage The BP scale is sometimes used for dates established by means other than radiocarbon dating, such as stratigraphy. This usage differs from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Settlement Of The Americas
The settlement of the Americas began when Paleolithic hunter-gatherers entered North America from the North Asian Mammoth steppe via the Beringia land bridge, which had formed between northeastern Siberia and western Alaska due to the lowering of sea level during the Last Glacial Maximum (26,000 to 19,000 years ago). These populations expanded south of the Laurentide Ice Sheet and spread rapidly southward, occupying both North and South America, by 12,000 to 14,000 years ago. The earliest populations in the Americas, before roughly 10,000 years ago, are known as Paleo-Indians. Indigenous peoples of the Americas have been linked to Siberian populations by linguistic factors, the distribution of blood types, and in genetic composition as reflected by molecular data, such as DNA. While there is general agreement that the Americas were first settled from Asia, the pattern of migration and the place(s) of origin in Eurasia of the peoples who migrated to the Americas remain unclear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clovis People
The Clovis culture is a prehistoric Paleoamerican culture, named for distinct stone and bone tools found in close association with Pleistocene fauna, particularly two mammoths, at Blackwater Locality No. 1 near Clovis, New Mexico, in 1936 and 1937 (though Paleoindian artifacts had been found at the site since the 1920s). It appears around 11,500–11,000 uncalibrated years before present (YBP)"Clovis Culture" entry in the ''Concise Oxford Dictionary of Archaeology'': "9,500–9,000 BC". at the end of the last glacial period and is characterized by the manufacture of " Clovis points" and distinctive bone and ivory tools. Archaeologists' most precise determinations at present suggest this radiocarbon age is equal to roughly 13,200 to 12,900 calendar years ago. The only human burial that has been directly associated with tools from the Clovis culture included the remains of an infant boy researchers named Anzick-1. Paleogenetic analyses of Anzick-1's ancient nuclear, mito ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Dating
Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was developed in the late 1940s at the University of Chicago by Willard Libby. It is based on the fact that radiocarbon () is constantly being created in the Earth's atmosphere by the interaction of cosmic rays with atmospheric nitrogen. The resulting combines with atmospheric oxygen to form radioactive carbon dioxide, which is incorporated into plants by photosynthesis; animals then acquire by eating the plants. When the animal or plant dies, it stops exchanging carbon with its environment, and thereafter the amount of it contains begins to decrease as the undergoes radioactive decay. Measuring the amount of in a sample from a dead plant or animal, such as a piece of wood or a fragment of bone, provides information that can be used to calc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valsequillo Gravels )
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Valsequillo may refer to the following places: * Valsequillo de Gran Canaria, a municipality on the island of Gran Canaria in the province of Las Palmas in the Canary Islands. * Valsequillo, Córdoba, a municipality and a village in the province of Córdoba * A reservoir and area south of Puebla, Mexico, known for its Pleistocene remains (see Hueyatlaco Hueyatlaco is an archeological site in the Valsequillo Basin near the city of Puebla, Mexico. After excavations in the 1960s, the site became notorious due to geochronologists' analyses that indicated human habitation at Hueyatlaco was dated to c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleomagnetism
Paleomagnetism (or palaeomagnetismsee ), is the study of magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain magnetic minerals in rocks can record the direction and intensity of Earth's magnetic field at the time they formed. This record provides information on the past behavior of the geomagnetic field and the past location of tectonic plates. The record of geomagnetic reversals preserved in volcanic and sedimentary rock sequences (magnetostratigraphy) provides a time-scale that is used as a geochronologic tool. Evidence from paleomagnetism led to the revival of the continental drift hypothesis and its transformation into the modern theory of plate tectonics. Apparent polar wander paths provided the first clear geophysical evidence for continental drift, while marine magnetic anomaly, magnetic anomalies did the same for seafloor spreading. Paleomagnetic data continues t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickly on the surface. For this reason, olivine has been proposed as a good candidate for accelerated weathering to sequester carbon dioxide from the Earth's oceans and atmosphere, as part of climate change mitigation. Olivine also has many other historical uses, such as the gemstone peridot (or chrysolite), as well as industrial applications like metalworking processes. The ratio of magnesium to iron varies between the two endmembers of the solid solution series: forsterite (Mg-endmember: ) and fayalite (Fe-endmember: ). Compositions of olivine are commonly expressed as molar percentages of forsterite (Fo) and fayalite (Fa) (''e.g.'', Fo70Fa30). Forsterite's melting temperature is unusually high at atmospheric pressure, almost , while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hueyatlaco
Hueyatlaco is an archeological site in the Valsequillo Basin near the city of Puebla, Mexico. After excavations in the 1960s, the site became notorious due to geochronologists' analyses that indicated human habitation at Hueyatlaco was dated to ca. 250,000 years before the present. These controversial findings are orders of magnitude older than the scientific consensus for habitation of the New World (which generally traces widespread human migration to the New World to 13,000 to 16,000 ybp). The findings at Hueyatlaco are the subject of continued debate by the scientific community, and have seen only occasional discussion in the literature.Gonzalez, Silvia; Huddart, David; and Bennett Matthew. (2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
