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91-538: International Commission on Stratigraphy (ICS) appointed working groups on the boundaries of the Ordovician subdivisions in 1974. The boundaries were established by the fauna of conodonts and/or graptolites . In 1995, the Subcommission on Ordovician Stratigraphy, with the support of 90% majority of voting members, adopted the division of the Ordovician system into three series: Lower, Middle and Upper . In

182-561: A writing system , built huge pyramids and temples , had a complex calendar , and developed the concept of zero around 400 CE. The first recorded European references to North America are in Norse sagas where it is referred to as Vinland . The earliest verifiable instance of pre-Columbian trans-oceanic contact by any European culture with the North America mainland has been dated to around 1000 CE. The site , situated at

273-597: A part of Denmark) and Mexico classified as Latin American). It is unknown with certainty how and when first human populations first reached North America. People were known to live in the Americas at least 20,000 years ago, but various evidence points to possibly earlier dates. The Paleo-Indian period in North America followed the Last Glacial Period, and lasted until about 10,000 years ago when

364-664: A period of mountain building called the Laramide orogeny , between 80 and 55 mya. The formation of the Isthmus of Panama that connected the continent to South America arguably occurred approximately 12 to 15 mya, and the Great Lakes (as well as many other northern freshwater lakes and rivers) were carved by receding glaciers about 10,000 years ago. North America is the source of much of what humanity knows about geologic time periods. The geographic area that would later become

455-590: A powerful earthquake killed seven people in 2009. Volcanic eruptions are common in the region. In 1968, the Arenal Volcano , in Costa Rica, erupted and killed 87 people. Fertile soils from weathered volcanic lavas have made it possible to sustain dense populations in agriculturally productive highland areas. Central America has many mountain ranges ; the longest are the Sierra Madre de Chiapas ,

546-540: A variety of reactions, including curiosity, trading, cooperation, resignation, and resistance. The indigenous population declined substantially following European arrival, primarily due to the introduction of Eurasian diseases, such as smallpox , to which the indigenous peoples lacked immunity, and because of violent conflicts with Europeans. Indigenous culture changed significantly and their affiliation with political and cultural groups also changed. Several linguistic groups died out , and others changed quite quickly. On

637-883: Is a continent in the Northern and Western Hemispheres . North America is bordered to the north by the Arctic Ocean , to the east by the Atlantic Ocean , to the southeast by South America and the Caribbean Sea , and to the west and south by the Pacific Ocean . The region includes the Bahamas , Bermuda , Canada , the Caribbean , Central America , Clipperton Island , Greenland , Mexico , Saint Pierre and Miquelon , Turks and Caicos Islands , and

728-665: Is a very large continent that extends from north of the Arctic Circle to south of the Tropic of Cancer . Greenland, along with the Canadian Shield , is tundra with average temperatures ranging from 10 to 20 °C (50 to 68 °F), but central Greenland is composed of a very large ice sheet. This tundra radiates throughout Canada, but its border ends near the Rocky Mountains (but still contains Alaska) and at

819-524: Is an ancient craton which forms the geologic core of North America; it formed between 1.5 and 1.0 billion years ago during the Proterozoic eon. The Canadian Shield is the largest exposure of this craton. From the Late Paleozoic to Early Mesozoic eras, North America was joined with the other modern-day continents as part of the supercontinent Pangaea , with Eurasia to its east. One of

910-546: Is in present-day Panama at the Darien Gap on the Colombia -Panama border, placing almost all of Panama within North America. Alternatively, some geologists physiographically locate its southern limit at the Isthmus of Tehuantepec , Mexico, with Central America extending southeastward to South America from this point. The Caribbean islands, or West Indies, are considered part of North America. The continental coastline

1001-648: Is long and irregular. The Gulf of Mexico is the largest body of water indenting the continent, followed by Hudson Bay . Others include the Gulf of Saint Lawrence and the Gulf of California . Before the Central American isthmus formed, the region had been underwater. The islands of the West Indies delineate a submerged former land bridge , which had connected North and South America via what are now Florida and Venezuela . There are several islands off

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1092-561: Is part of North America geographically. In a geologic sense, Bermuda is not part of the Americas, but an oceanic island that was formed on the fissure of the Mid-Atlantic Ridge over 100 million years ago (mya). The nearest landmass to it is Cape Hatteras , North Carolina . However, Bermuda is often thought of as part of North America, especially given its historical, political and cultural ties to Virginia and other parts of

1183-707: Is the Morrison Formation of the western U.S. Canada is geologically one of the oldest regions in the world, with more than half of the region consisting of Precambrian rocks that have been above sea level since the beginning of the Palaeozoic era. Canada's mineral resources are diverse and extensive. Across the Canadian Shield and in the north there are large iron, nickel, zinc , copper, gold, lead, molybdenum , and uranium reserves. Large diamond concentrations have been recently developed in

1274-527: Is the humid subtropical climate . This area has the wettest cities in the contiguous U.S. , with annual precipitation reaching 67 in (1,700 mm) in Mobile, Alabama . Stretching from the borders of the humid continental and subtropical climates, and going west to the Sierra Nevada , south to the southern tip of Durango , north to the border with tundra climate, the steppe / desert climates are

1365-454: The Age of Discovery and the early modern period . Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples , enslaved Africans , immigrants from Europe, Asia, and descendants of these respective groups. Europe's colonization in North America led to most North Americans speaking European languages, such as English , Spanish , and French , and

1456-519: The Archaic period began. The classic stage followed the Archaic period, and lasted from approximately the 6th to 13th centuries. Beginning in 1000 AD, the Norse were the first Europeans to begin exploring and ultimately colonizing areas of North America. In 1492, the exploratory voyages of Christopher Columbus led to a transatlantic exchange , including migrations of European settlers during

1547-567: The Bering Strait during the Early-Middle Holocene . Prior to the arrival of European explorers and colonists in North America, the natives of North America were divided into many different polities, ranging from small bands of a few families to large empires. They lived in several culture areas , which roughly correspond to geographic and biological zones that defined the representative cultures and lifestyles of

1638-600: The British Columbia Coast , Western Canada , and Northern Canada . In the U.S., they include New England , the Mid-Atlantic , South Atlantic states , East North Central states , West North Central states , East South Central states , West South Central states , Mountain states , and Pacific states . The Great Lakes region and the Pacific Northwest include areas in both Canada and

1729-913: The Caribbean Plate , whereas the Juan de Fuca Plate and Cocos Plate border the North American Plate on its western frontier. The continent can be divided into four great regions (each of which contains many subregions): the Great Plains stretching from the Gulf of Mexico to the Canadian Arctic ; the geologically young, mountainous west, including the Rocky Mountains , the Great Basin , California , and Alaska ;

1820-568: The Cordillera Isabelia , and the Cordillera de Talamanca . Between the mountain ranges lie fertile valleys that are suitable for the people; in fact, most of the population of Honduras, Costa Rica, and Guatemala live in valleys. Valleys are also suitable for the production of coffee, beans, and other crops. The indigenous peoples of the Americas have many creation myths , based on which they assert that they have been present on

1911-465: The East Coast to eastern North Dakota , and stretching down to Kansas , is the humid continental climate featuring intense seasons, with a large amount of annual precipitation, with places like New York City averaging 50 in (1,300 mm). Starting at the southern border of the humid continental climate and stretching to the Gulf of Mexico (whilst encompassing the eastern half of Texas)

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2002-695: The International Stratigraphic Chart , a combined working proposal and guideline-to-date released after the last ICS deliberations prior to the upcoming (next) meeting of the IUGS. Until the IUGS accepts the recommendations, they are unofficial since the IUGS parent approves or dismisses the individual deliberation reports of the ICS, which are presented as recommendations, and span dating and strata selection criteria, and related issues including nomenclatures. In de facto everyday matters,

2093-558: The International Union of Geological Sciences (IUGS) proposed to deny the use of specific points and replace them by Standard Auxiliary Boundary Stratotypes (SABS) for more "flexible" correlations with GSSPs. The global stages of the Lower Ordovician, as well as of other series, are also subdivided into stage slices (time slices), which are corresponding to the base of conodont or graptolite zones. In addition to

2184-620: The Inuit of the high Arctic arrived in North America much later than other native groups, evidenced by the disappearance of Dorset culture artifacts from the archaeological record and their replacement by the Thule people . During the thousands of years of native habitation on the continent, cultures changed and shifted. One of the oldest yet discovered is the Clovis culture (c. 9550–9050 BCE) in modern New Mexico . Later groups include

2275-719: The Mississippian culture and related Mound building cultures, found in the Mississippi River valley and the Pueblo culture of what is now the Four Corners . The more southern cultural groups of North America were responsible for the domestication of many common crops now used around the world, such as tomatoes, squash , and maize . As a result of the development of agriculture in the south, many other cultural advances were made there. The Mayans developed

2366-817: The Neogene System and Neogene Period. Despite the strong debate, the Quaternary saw official ratification as a geological unit from the IUGS in June 2009, placing its lower boundary to the Gelasian Stage/Age at Monte San Nicola, Sicily, Italy (until then uppermost part of the Pliocene Series/Epoch, and thus of the Neogene System/Period), 2.58 Ma BP . In addition to publishing paper and document (PDF) versions of

2457-540: The Phanerozoic eon. This event occurred at different intervals depending on the groups of organisms and the geographical region, and, in fact, the GOBE refers to a whole complex of sequential and interconnected processes of evolution and migration of organisms. The first phase, associated with planktonic communities, probably began in the late Cambrian and ended in the late Early Ordovician. The Early Ordovician marks

2548-757: The USA , Canada , Greenland , Scotland and partly Ireland . Laurentia was located in the tropical latitudes of the southern hemisphere; today's central Nevada and western Utah were covered by sea waters at the end of the Early Ordovician. In 2007, Bassett et al. analyzed the oxygen isotope values of Early Ordovician strata of the Lange Ranch section in central Texas and concluded that tropical sea temperatures at that time could have reached 37°C or 42°C. Similar results were recovered by Trotter et al. in 2008, after oxygen isotope analysis of conodonts from

2639-516: The United States . North America covers an area of about 24,709,000 square kilometers (9,540,000 square miles), representing approximately 16.5% of the Earth 's land area and 4.8% of its total surface area. It is the third-largest continent by size after Asia and Africa , and the fourth-largest continent by population after Asia, Africa, and Europe . As of 2021 , North America's population

2730-714: The first appearance datum (FAD) of the conodont Iapetognathus fluctivagus at the 101.8 m above the base of the outcrop. Doubts have been expressed about the identification of the index taxon, but it occurs below the Rhabdinopora and related graptolites. The GSSP of the Floian , the second and last stage of the Lower Ordovician, is established in the Diabasbrottet Quarry , Sweden , ( 58°21′32″N 12°30′09″E  /  58.3589°N 12.5024°E  / 58.3589; 12.5024 ) and defined by FAD of

2821-488: The first official name given to Mexico. North America includes several regions and subregions, each of which have their own respective cultural, economic, and geographic regions. Economic regions include several regions formalized in 20th- and 21st-century trade agreements, including NAFTA between Canada , Mexico , and the United States , and CAFTA between Central America , the Dominican Republic , and

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2912-695: The graptolite Tetragraptus approximatus . Two Auxiliary boundary Stratotype Sections and Points (ASSPs) were also established for the Lower Ordovician/Tremadocian: the first one in the Lawson Cove section in Millard County, Utah , USA , and the second one in the Xiaoyangqiao section, North China . Both ASSPs were approved by the Subcommission on Ordovician Stratigraphy in 2016 and 2019, respectively, but, in 2021,

3003-556: The paleontology , geology , geobiology and chronostratigraphy fields, among others. The International Commission on Stratigraphy has spawned numerous subcommittee level organizations organized and mobilized on a local country-wide or regional basis that are the true working committees of the IUGS, and these do the field work, basis comparisons in conference or co-ordination research committee meetings of local or wide-scale scope. The ICS publishes various reports and findings as well as revised references periodically, summarized in

3094-426: The " International Stratigraphic Commission ", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphical , geological , and geochronological matters on a global scale. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working subcommittee , which meets far more regularly than

3185-458: The 1490s, building cities, putting the resident indigenous populations to work, raising crops for Spanish settlers and panning gold to enrich the Spaniards. Much of the indigenous population died due to disease and overwork, spurring the Spaniards on to claim new lands and peoples. An expedition under the command of Spanish settler, Hernán Cortés , sailed westward in 1519 to what turned out to be

3276-630: The Arctic, making Canada one of the world's largest producers. Throughout the Shield, there are many mining towns extracting these minerals. The largest, and best known, is Sudbury , Ontario. Sudbury is an exception to the normal process of forming minerals in the Shield since there is significant evidence that the Sudbury Basin is an ancient meteorite impact crater . The nearby, but less-known Temagami Magnetic Anomaly has striking similarities to

3367-524: The Australian scale, the global Lower Ordovician roughly corresponds to the Lancefieldian, Bendigonian, Chewtonian and lower Castlemainian stages. The Iapetus Ocean , located between Gondwana , Laurentia and Baltica , reached over 4000 km in width at the beginning of the Ordovician. In the north, between eastern Laurentia and Siberia, it connected with Panthalassa , which covered about half

3458-651: The Caribbean islands. France took the western half of Hispaniola and developed Saint-Domingue as a cane sugar producing colony worked by black slave labor. Britain took Barbados and Jamaica , and the Dutch and Danes took islands previously claimed by Spain. Britain did not begin settling on the North American mainland until a hundred years after the first Spanish settlements, since it sought first to control nearby Ireland . The first permanent English settlement

3549-635: The Cod fish", in reference to the abundance of cod fish on the East Coast . Waldseemüller used the Latin version of Vespucci's name, Americus Vespucius, in its feminine form of "America", following the examples of "Europa", "Asia", and "Africa". Americus originated from Medieval Latin Emericus (see Saint Emeric of Hungary ), coming from the Old High German name Emmerich . Map makers later extended

3640-524: The Early Ordovician, this territory was located near the paleocontinent of Laurentia. Oil and gas exploration is underway in the Early Ordovician Tongzi and Meitan formations in Sichuan Basin and the Early Ordovician strata of the Tarim Basin, China. In the Lower Ordovician of the Tarim Basin near Tazhong , oil accumulations are found at depths of up to 9000 m. International Commission on Stratigraphy The International Commission on Stratigraphy ( ICS ), sometimes unofficially referred to as

3731-452: The International Stratigraphic Chart, the ICS also provides a machine-readable version of the chart formulated using the Web Ontology Language (OWL) and, in particular, Time Ontology in OWL . The ICS' chart web page also provides an interactive version of the chart, based on the OWL data. The logo of International Commission on Stratigraphy was designed after the Chinese character of "mountain", 山. North America North America

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3822-419: The North America's southeastern coast, Spanish explorer Juan Ponce de León , who had accompanied Columbus's second voyage, visited and named in 1513 La Florida . As the colonial period unfolded, Spain, England, and France appropriated and claimed extensive territories in North America eastern and southern coastlines. Spain established permanent settlements on the Caribbean islands of Hispaniola and Cuba in

3913-469: The Ollo de Sapo magmatic event occurred on the northwestern territory of Gondwana , which is now the Iberian Peninsula . In Early Ordovician (Floian) strata of the San Juan Formation, Argentina , the oldest microfossils , known as calcisphers or calcitarchs , are present. Early forms reached 80 to 250 μm in diameter. Some of these organisms are probably algae . Calcitarchs lived in the subtidal zone , from coastal waves to shoals and reefs . Algae of

4004-457: The Ordovician was divided into six series, of which the lower one, the Tremadocian , passed into the International Stratigraphic Chart (ISC) as the stage of the same name. The upper Arenig series corresponds to the upper part of the Lower and lower part of the Middle Ordovician global series. On the British chart, the boundaries of Ordovician subdivisions are determined by local stratigraphic and paleontological features that are poorly defined in

4095-437: The Ordovician. Tariccoia tazagurtensis is a member of this arthropod clade from the Lower Ordovician of Morocco. In the same Fezouata Formation, Aegirocassis was discovered. This filter feeder arthropod reached over 2 m in length and was the largest animal of its time . Marrellomorphs , appeared in Cambrian, continued to exist in Early Ordovician. Soft-bodied and shelly organisms, including Cambrian relics as well as

4186-416: The Sudbury Basin. Its magnetic anomalies are very similar to the Sudbury Basin, and so it could be a second metal-rich impact crater. The Shield is also covered by vast boreal forests that support an important logging industry. The United States can be divided into twelve main geological provinces: Each province has its own geologic history and unique features. The geology of Alaska is typical of that of

4277-410: The U.S. North America occupies the northern portion of the landmass generally referred to as the New World, the Western Hemisphere , the Americas, or simply America, which, in many countries, is considered a single continent with North America a subcontinent . North America is the third-largest continent by area after Asia and Africa . North America's only land connection to South America

4368-429: The United States has been the source of more varieties of dinosaurs than any other modern country. According to paleontologist Peter Dodson, this is primarily due to stratigraphy, climate and geography, human resources, and history. Much of the Mesozoic Era is represented by exposed outcrops in the many arid regions of the continent. The most significant Late Jurassic dinosaur-bearing fossil deposit in North America

4459-550: The United States, and Mexico. France , Italy , Portugal , Spain , Romania , Greece , and the countries of Latin America use a six-continent model , with the Americas viewed as a single continent and North America designating a subcontinent comprising Canada , the United States , Mexico, and Saint Pierre and Miquelon (politically part of France), and often including Greenland and Bermuda . North America has historically been known by other names, including Spanish North America, New Spain , and América Septentrional,

4550-527: The United States. North America is divided linguistically and culturally into two primary regions, Anglo-America and Latin America . Anglo-America includes most of North America, Belize , and Caribbean islands with English -speaking populations. There are also regions, including Louisiana and Quebec , with large Francophone populations; in Quebec , French is the official language. . The southern portion of North America includes Central America and non-English speaking Caribbean nations. The north of

4641-435: The area had shifted to the Aztec Empire , whose capital city Tenochtitlan was located further north in the Valley of Mexico . The Aztecs were conquered in 1521 by Hernán Cortés . During the so-called Age of Discovery , Europeans explored overseas and staked claims to various parts of North America, much of which was already settled by indigenous peoples. Upon Europeans' arrival in the " New World ", indigenous peoples had

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4732-437: The beginning of the second phase, which affected the inhabitants of benthos . One of the possible signs of the GOBE is the fossil reefs found in the Early Ordovician Dumugol Formation , South Korea . This reefs, built by the microorganisms and sponges of the genus Archaeoscyphia , are different from the Cambrian and early Tremadocian and this discovery confirm that reef communities occupied deeper-sea habitats as early as in

4823-432: The continent maintains recognized regions as well. In contrast to the common definition of North America, which encompasses the whole North American continent, the term "North America" is sometimes used more narrowly to refer only to four nations, Canada, Greenland, Mexico, and the U.S. The U.S. Census Bureau includes Saint Pierre and Miquelon, but excludes Mexico from its definition. The term Northern America refers to

4914-452: The continent's coasts; principally, the Arctic Archipelago, the Bahamas , Turks and Caicos , the Greater and Lesser Antilles , the Aleutian Islands (some of which are in the Eastern Hemisphere proper), the Alexander Archipelago , the many thousand islands of the British Columbia Coast, and Newfoundland. Greenland , a self-governing Danish island, and the world's largest , is on the same tectonic plate (the North American Plate ) and

5005-410: The continent. The vast majority of North America is on the North American Plate. Parts of western Mexico, including Baja California, and of California , including the cities of San Diego , Los Angeles , and Santa Cruz , lie on the eastern edge of the Pacific Plate , with the two plates meeting along the San Andreas Fault . The southernmost portion of the continent and much of the West Indies lie on

5096-604: The cordillera, while the major islands of Hawaii consist of Neogene volcanics erupted over a hot spot . Central America is geologically active with volcanic eruptions and earthquakes occurring from time to time. In 1976 Guatemala was hit by a major earthquake , killing 23,000 people; Managua, the capital of Nicaragua, was devastated by earthquakes in 1931 and 1972, the last one killing about 5,000 people; three earthquakes devastated El Salvador, one in 1986 and two in 2001; one earthquake devastated northern and central Costa Rica in 2009, killing at least 34 people; in Honduras

5187-514: The cultures of the region commonly reflect Western traditions . However, relatively small parts of North America in Canada, the United States, Mexico, and Central America have indigenous populations that continue adhering to their respective pre-European colonial cultural and linguistic traditions. The Americas were named after the Italian explorer Amerigo Vespucci by German cartographers Martin Waldseemüller and Matthias Ringmann . Vespucci explored South America between 1497 and 1502, and

5278-469: The deep-water sediments of the Early Ordovician (Floian) Al Rose Formation in the Inyo Mountains , California , the trilobite fauna have been discovered. Despite the low species diversity, this fauna is unique due to differences in the composition of families from more eastern complexes of the comparable age. Fossils identified as belonging to the Globampyx , Protopresbynileus , Carolinites , Cloacaspis , Geragnostus and Hintzeia genera. In

5369-438: The deliberative results reported out of any meetings of the ICS are widely accepted and immediately enter everyday use, except in the rare cases where they result in a strong body of dissenting opinion, which matters are resolved before the full IUGS. One such controversy arose in 2009 when the ICS deliberated and decided that the Pliocene Series of the current but unofficially named Quaternary Period should be shifted into

5460-447: The driest in the U.S. Highland climates cut from north to south of the continent, where subtropical or temperate climates occur just below the tropics, as in central Mexico and Guatemala . Tropical climates appear in the island regions and in the subcontinent's bottleneck, found in countries and states bathed by the Caribbean Sea or to the south of the Gulf of Mexico and the Pacific Ocean . Precipitation patterns vary across

5551-409: The end of the Middle Ordovician , the surface of the low-latitude seas had cooled to temperatures comparable to today's equatorial ones. The Great Ordovician Biodiversification Event (GOBE), manifested in an increase in the diversity of marine life, occurred in Early Ordovician. Along with the Cambrian explosion and radiation in the early Mesozoic , it is the most significant biodiversification in

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5642-408: The end of the Canadian Shield, near the Great Lakes . Climate west of the Cascade Range is described as being temperate weather with average precipitation 20 inches (510 millimeters). Climate in coastal California is described to be Mediterranean , with average temperatures in cities like San Francisco ranging from 57 to 70 °F (14 to 21 °C) over the course of the year. Stretching from

5733-421: The first American inhabitants sailed from Beringia some 13,000 years ago, with widespread habitation of the Americas during the end of the Last Glacial Period , in what is known as the Late Glacial Maximum , around 12,500 years ago. The oldest petroglyphs in North America date from 15,000 to 10,000 years before present. Genetic research and anthropology indicate additional waves of migration from Asia via

5824-598: The fossil record. (i.e. section of the rock record as of a core sample section or accessible exposed strata, which when a core sample are usually "trayed" in long pieces, also called "sections" about a meter in length.) Additionally the ICS defines an alternative type of benchmark and criteria called Global Standard Stratigraphic Ages (GSSAs) where the characteristics and dating criteria set solely by physical sciences methods (such as magnetic alignment sequences, radiological criteria, etcetera.) as well as encouraging an international and open debate amongst Earth scientists in

5915-406: The four paleoplates located in the Early Ordovician at low latitudes. Authors of the 2021 article give values in accordance with the study by Song et al. (2019): from 43.9°C 485 million years ago to 37.1°C 470 million years ago. High temperatures that persisted throughout the Early Ordovician affected the biodiversification later, in the Middle Ordovician. CO 2 level in Early Ordovician atmosphere

6006-457: The genus Amsassia appeared. They already lived off the southern coast of Laurentia and Cuyania in the Early Ordovician, and later occupied an even wider range and disappeared only during the Ordovician-Silurian extinction . In Tremadocian, Amsassia inhabited small reefal mounds in shallow sea waters. Discovered in the Floian strata of Newfoundland , coral-like fossils of Reptamsassia divergens and Reptamsassia minuta allows to judge

6097-795: The geographic center of either the 50 states, the conterminous United States, or the North American continent." Nonetheless, there is a 4.6-meter (15 ft) field stone obelisk in Rugby claiming to mark the center. The North American continental pole of inaccessibility is located 1,650 km (1,030 mi) from the nearest coastline, between Allen and Kyle, South Dakota at 43°22′N 101°58′W  /  43.36°N 101.97°W  / 43.36; -101.97  ( Pole of Inaccessibility North America ) . Canada can be divided into roughly seven physiographic divisions: The lower 48 U.S. states can be divided into roughly eight physiographic divisions: Mexico can be divided into roughly fifteen physiographic divisions: North America

6188-463: The global stages, the Tetragraptus approximatus Zone is also defined in the regional subdivisions of the UK and Australia , and the Didymograptus protobifidus Zone in those of North America , Australia and Baltoscandia . The following conodont zones are distinguished in Early Ordovician deposits of Boothia Peninsula , Canada (from upper to lower): Graptolite (g) and conodont (c) zonal subdivisions of southern Siberia (from upper to lower): On

6279-419: The indigenous people who lived there, including the bison hunters of the Great Plains and the farmers of Mesoamerica . Native groups also are classified by their language families , which included Athapascan and Uto-Aztecan languages. Indigenous peoples with similar languages did not always share the same material culture , however, and were not necessarily always allies. Anthropologists speculate that

6370-400: The land since its creation, but there is no evidence that humans evolved there. The specifics of the initial settlement of the Americas by ancient Asians are subject to ongoing research and discussion. The traditional theory has been that hunters entered the Bering Land Bridge between eastern Siberia and present-day Alaska from 27,000 to 14,000 years ago. A growing viewpoint is that

6461-620: The level of development of reef ecosystems of the Early Ordovician, since they are the oldest example of symbiotic intergrowth of modular species. Echinoderm diversity increased in the Early Ordovician: new classes appeared, including asteroids , ophiuroids , crinoids and diploporitans . Various Early Ordovician echinoderms are found in the Fillmore Formation in Utah , USA, Fezouata Formation in Anti-Atlas , Morocco, and Saint-Chinian Formation in Montagne Noire , France. Nektaspida have become less diverse after Cambrian. They most likely inhabited restricted or colder brackish seas in

6552-657: The mainland in Mexico. With local indigenous allies, the Spanish conquered the Aztec empire in central Mexico in 1521. Spain then established permanent cities in Mexico, Central America, and Spanish South America in the sixteenth century. Once Spaniards conquered the high civilization of the Aztecs and Incas, the Caribbean was a backwater of the Spanish empire. Other European powers began to intrude on areas claimed by Spain, including

6643-475: The middle Tremadocian. The radiation of marine life during the GOBE in the Early Ordovician was resulted by the transition from sulphidic to oxic conditions in the oceans of that time. Substantial older ("pre-GOBE") radiations are observed in the Early Ordovician sediments of South China . However, it is questionable, were they global or not. From the Furongian to the end of the Early Ordovician, 495-470 Ma,

6734-927: The middle into the main range of the Rockies and the coast ranges in California , Oregon , Washington , and British Columbia , with the Great Basin—a lower area containing smaller ranges and low-lying deserts—in between. The highest peak is Denali in Alaska. The U.S. Geographical Survey (USGS) states that the geographic center of North America is "6 miles [10 km] west of Balta, Pierce County, North Dakota " at about 48°10′N 100°10′W  /  48.167°N 100.167°W  / 48.167; -100.167 , about 24 kilometers (15 mi) from Rugby, North Dakota . The USGS further states that "No marked or monumented point has been established by any government agency as

6825-454: The name America to North America. In 1538, Gerardus Mercator used the term America on his world map of the entire Western Hemisphere . On his subsequent 1569 map , Mercator called North America "America or New India" ( America sive India Nova ). The Spanish Empire called its territories in North and South America "Las Indias", and the name given to the state body that oversaw the region

6916-590: The new taxa of the Ordovician origin, constitute a fossil Liexi fauna , preserved in the Lower Ordovician Madaoyu Formation of Hunan , South China . Fossil specimens include bryozoans , sponges , echinoderms, polychaetes , graptolites , trilobites and conodonts . Palaeoscolecidan worms, including Liexiscolex and a possible Ottoia specimen, are of great interest. Early Ordovician priapulids , similar to their Cambrian predecessors, are also known from northern China. In

7007-493: The northernmost countries and territories of North America: the U.S., Bermuda , Canada, Greenland, and St. Pierre and Miquelon. Although the term does not refer to a unified region, Middle America includes Mexico, Central America, and the Caribbean. North America's largest countries by land area are Canada and the U.S., both of which have well-defined and recognized subregions. In Canada, these include (from east to west) Atlantic Canada , Central Canada , Canadian Prairies ,

7098-440: The northernmost extent of the island named Newfoundland , has provided unmistakable evidence of Norse settlement. Norse explorer Leif Erikson (c. 970–1020 CE) is thought to have visited the area. Erikson was the first European to make landfall on the continent (excluding Greenland). The Mayan culture was still present in southern Mexico and Guatemala when the Spanish conquistadors arrived, but political dominance in

7189-466: The planet. Formed in late Cambrian, Rheic Ocean stretched between Gondwana and the microcontinent of Avalonia . Cuyania (northwest of today's Argentina ) was located at low latitudes. Gondwana, already a large continent, consisted of today's South America , Africa , the Arabian Peninsula , India, eastern Australia and eastern Antarctica . Laurentia included the territories of Mexico ,

7280-442: The quadrennial meetings scheduled by the IUGS, when it meets as a congress or membership of the whole . One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontological and geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype Section and Points (GSSPs) within

7371-605: The raised but relatively flat plateau of the Canadian Shield in the northeast; and the varied eastern region, which includes the Appalachian Mountains, the coastal plain along the Atlantic seaboard, and the Florida peninsula. Mexico, with its long plateaus and cordilleras , falls largely in the western region, although the eastern coastal plain does extend south along the Gulf. The western mountains are split in

7462-500: The region, and as such rainforest , monsoon , and savanna types can be found, with rains and high temperatures throughout the year. Notable North American fauna include the bison , black bear , jaguar , cougar , prairie dog , turkey , pronghorn , raccoon , coyote , and monarch butterfly . Notable plants that were domesticated in North America include tobacco , maize , squash , tomato , sunflower , blueberry , avocado , cotton , chile pepper , and vanilla . Laurentia

7553-512: The rest of the world. As a result, local series and stages, very different from the British standard, were identified on different paleoplates or modern continents. In 2008, the traditional British Ordovician subdivisions were replaced by seven new stages with defined GSSPs. Tremadocian and Floian stages were included in the Lower Ordovician series. In 2011, the Russian regional stratigraphic chart

7644-487: The results of the formation of Pangaea was the Appalachian Mountains , which formed some 480 mya, making it among the oldest mountain ranges in the world. When Pangaea began to rift around 200 mya, North America became part of Laurasia , before it separated from Eurasia as its own continent during the mid- Cretaceous period. The Rockies and other western mountain ranges began forming around this time from

7735-426: The same year, it was decided to divide each of the three series into two global stages. Tetragraptus approximatus zone was chosen as the base of the upper stage of the Lower Ordovician by 95% of the votes. Before the adoption of the international standard, the series from the chart of Britain, the type locality of the Ordovician system, were accepted by default as Ordovician subdivisions. In accordance with this scale,

7826-549: Was called the Council of the Indies . The United Nations and its statistics division recognize North America as including three regions: Northern America, Central America , and the Caribbean . "Northern America" is a distinct term from "North America", excluding Central America, which itself may or may not include Mexico . In the limited context of regional trade agreements, the term is used to reference three nations: Canada,

7917-657: Was changed from the British to the international standard division of the Ordovician system. The Global Boundary Stratotype Section and Point (GSSP) of the Lower Ordovician, which is also a GSSP of the Tremadocian stage and the whole Ordovician system, is established in the Green Point section in the west of the Newfoundland , Canada ( 49°40′58″N 57°57′55″W  /  49.6829°N 57.9653°W  / 49.6829; -57.9653 ) and corresponds to

8008-624: Was estimated as over 592 million people in 23 independent states , or about 7.5% of the world's population. In human geography , the terms "North America" and "North American" can refer to Canada, the United States, Mexico, and Greenland or, alternatively, Canada, Greenland and the US (Mexico being classified as part of Latin America ) or simply Canada and the US (Greenland being classified as either Arctic or European (due to its political status as

8099-421: Was high while oxygen levels varied from approximately 10% to 13%. Studies of oxygen isotopes from apatites (particularly conodont apatites from Nevada and Utah) show that at the end of the Early Ordovician the climate began to change from greenhouse to icehouse . These changes occurred gradually and were accompanied by fluctuations in sea surface temperature with an approximate duration of 10 to 10 years. By

8190-817: Was in Jamestown, Virginia in 1607, followed by additional colonial establishments on the east coast from present-day Georgia in the south to Massachusetts in the north, forming the Thirteen Colonies of British America. The English did not establish settlements north or east of the St. Lawrence Valley in present-day Canada until after the conclusion of the American Revolutionary War . Britain's early settlements in present-day Canada included St. John's, Newfoundland in 1630 and Halifax, Nova Scotia in 1749. The first permanent French settlement

8281-473: Was the first European to suggest that the Americas represented a landmass not then known to the Europeans. In 1507, Waldseemüller published a world map, and placed the word "America" on the continent of present-day South America. The continent north of present-day Mexico was then referred to as Parias. On a 1553 world map published by Petrus Apianus , North America was called "Baccalearum", meaning "realm of

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