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28-487: The Chapada Diamantina lies at the center of Bahia State and forms the northern part of the Espinhaço Mountain Range . The region is approximately 38,000 km (15,000 sq mi) in area and encompasses 58 municipalities. Technically, this region is considered a part of the caatinga biome , and contains some of its highest elevations, most of it above 500 metres (1,600 ft). The vegetation ;

56-708: A supereon , but this is also an informal term, not defined by the ICS in its chronostratigraphic guide. Eozoic (from eo- "earliest") was a synonym for pre-Cambrian , or more specifically Archean . A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks (Archean Eon) from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia . Probable fossils 100 million years older have been found in

84-960: A mountain range in Brazil . The range runs roughly north and south through the states of Minas Gerais and Bahia , extending for approximately 1,100 km (680 mi). It forms the divide between the upper watershed of the São Francisco River and those of the shorter rivers which flow east into the Atlantic Ocean , including the Doce , the Jequitinhonha , and the Pardo rivers. Pico do Sol , its highest peak, rises to 2,072 metres (6,798 ft), in Catas Altas town ( Caraça National Park ). The historical town of Diamantina

112-735: A possible 2450 Ma red alga from the Kola Peninsula , 1650 Ma carbonaceous biosignatures in north China, the 1600 Ma Rafatazmia , and a possible 1047 Ma Bangiomorpha red alga from the Canadian Arctic. The earliest fossils widely accepted as complex multicellular organisms date from the Ediacaran Period. A very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota . Hard-shelled creatures appeared toward

140-508: A product of the physiographic conditions, is known as cerrado , and consists of rocky plains, dry forests, and caatinga desert vegetation, all of which harbour a great deal of biodiversity and unique endemisms . The region is considered to have a Mesotermic climate, of the Cwb type, according to Köppen Climate classifications . It is normally quite cooler than its surrounding areas, with an average annual temperature under 22 °C. The territory of

168-722: Is composed primarily of sandstone , pelites and diamond bearing conglomerates. The Paraguaçu is composed of fine-grained sandstones, siltstones and argillites . The rocks of the Paraguaçu are softer and therefore more susceptible to weathering and folding. It is the folds in the Paraguaçu that allows for the entry of water into the rock’s structure which in turn is responsible for the erosion. 12°52′49″S 41°22′20″W  /  12.8803°S 41.3722°W  / -12.8803; -41.3722 Espinha%C3%A7o Mountains The Espinhaço Mountains ( Portuguese : Serra do Espinhaço , IPA: [ˈsɛʁɐ dwispiˈɲasu] ) are

196-664: Is known to occur during the RNA replication of extant coronaviruses . Evidence of the details of plate motions and other tectonic activity in the Precambrian is difficult to interpret. It is generally believed that small proto-continents existed before 4280 Ma, and that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia , broke up around 750 Ma. A number of glacial periods have been identified going as far back as

224-718: Is located in the Espinhaço Mountains. The Espinhaço Mountains were a major route through which Minas Gerais was settled during the Gold Rush of the 18th century. This Bahia , Brazil location article is a stub . You can help Misplaced Pages by expanding it . This geographical article relating to Minas Gerais is a stub . You can help Misplaced Pages by expanding it . Precambrian The Precambrian ( / p r i ˈ k æ m b r i . ə n , - ˈ k eɪ m -/ pree- KAM -bree-ən, -⁠KAYM- ; or Pre-Cambrian , sometimes abbreviated pC , or Cryptozoic )

252-668: Is the earliest part of Earth's history , set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian , the first period of the Phanerozoic Eon , which is named after Cambria , the Latinized name for Wales , where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons ( Hadean , Archean , Proterozoic ) of

280-521: Is thought that the Earth coalesced from material in orbit around the Sun at roughly 4,543 Ma, and may have been struck by another planet called Theia shortly after it formed, splitting off material that formed the Moon (see Giant-impact hypothesis ). A stable crust was apparently in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma. The term "Precambrian"

308-731: Is used by geologists and paleontologists for general discussions not requiring a more specific eon name. However, both the United States Geological Survey and the International Commission on Stratigraphy regard the term as informal. Because the span of time falling under the Precambrian consists of three eons (the Hadean , the Archean , and the Proterozoic ), it is sometimes described as

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336-534: The Huronian epoch, roughly 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a " Snowball Earth ". The atmosphere of the early Earth is not well understood. Most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and

364-884: The Precambrian eon . The Range System has an erosional outlier that exposes a contact, the Pai Inácio anticline . The Pai Inácio Anticline is 25 km wide and exposes the sedimentary rocks of the Paraguaçu Group . At the contact there are two different rock groups exposed one being the Chapada Diamantina and the Paraguaçu, with the Chapada Diamantina overlying the Paraguaçu Group. These two rock formations group not only in elasticity but in composition as well. The Chapada Diamantina

392-522: The geologic time scale . It spans from the formation of Earth about 4.6 billion years ago ( Ga ) to the beginning of the Cambrian Period, about 538.8 million years ago ( Ma ), when hard-shelled creatures first appeared in abundance. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earth's history , and what is known has largely been discovered from

420-482: The oxygen catastrophe . At first, oxygen would have quickly combined with other elements in Earth's crust, primarily iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, and the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering

448-401: The 1960s onwards. The Precambrian fossil record is poorer than that of the succeeding Phanerozoic , and fossils from the Precambrian (e.g. stromatolites ) are of limited biostratigraphic use. This is because many Precambrian rocks have been heavily metamorphosed , obscuring their origins, while others have been destroyed by erosion, or remain deeply buried beneath Phanerozoic strata. It

476-428: The Chapada Diamantina runs roughly between the cities of Mucugê ( 13°00′S 41°22′W  /  13.000°S 41.367°W  / -13.000; -41.367 ) to the south, Andaraí ( 12°48′S 41°20′W  /  12.800°S 41.333°W  / -12.800; -41.333 ) in the southeast, Lençóis ( 12°33′S 41°23′W  /  12.550°S 41.383°W  / -12.550; -41.383 ) in

504-405: The city of Lençóis and at Vale do Capão, district of Palmeiras and at Igatu , district of Andaraí. Lençóis, one of the main cities, is 428 kilometres (266 miles) from Salvador and can be reached by car, bus or plane. Another important city is Iraquara . It has a lot of caves, where prehistoric rock art and other evidence of early human habitation can be found. For this reason, Iraquara received

532-401: The current scheme based upon numerical ages. Such a system could rely on events in the stratigraphic record and be demarcated by GSSPs . The Precambrian could be divided into five "natural" eons, characterized as follows: The movement of Earth's plates has caused the formation and break-up of continents over time, including occasional formation of a supercontinent containing most or all of

560-453: The early years of the Earth's existence, as radiometric dating has allowed absolute dates to be assigned to specific formations and features. The Precambrian is divided into three eons: the Hadean (4567.3–4031 Ma), Archean (4031-2500 Ma) and Proterozoic (2500-538.8 Ma). See Timetable of the Precambrian . It has been proposed that the Precambrian should be divided into eons and eras that reflect stages of planetary evolution, rather than

588-705: The end of that time span, marking the beginning of the Phanerozoic Eon. By the middle of the following Cambrian Period, a very diverse fauna is recorded in the Burgess Shale , including some which may represent stem groups of modern taxa. The increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Tracks from an animal with leg-like appendages have been found in what

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616-541: The landmass. The earliest known supercontinent was Vaalbara . It formed from proto-continents and was a supercontinent 3.636 billion years ago. Vaalbara broke up c. 2.845–2.803 Ga ago. The supercontinent Kenorland was formed c. 2.72 Ga ago and then broke sometime after 2.45–2.1 Ga into the proto-continent cratons called Laurentia , Baltica , Yilgarn craton and Kalahari . The supercontinent Columbia , or Nuna, formed 2.1–1.8 billion years ago and broke up about 1.3–1.2 billion years ago. The supercontinent Rodinia

644-587: The most important cities in the area, one can find quite a few ecotourism agencies as well as independent guides. Among the main attractions are the Morro do Pai Inácio (Pai Inácio Hill), Cachoeira da Fumaça , Mixila Waterfall, Sossego Waterfall and the Vale do Pati which is considered the best trekking destination in the country. Rock climbing is a relatively new activity, but is developing quickly as some local and outside climbers are opening more and more routes, mainly in

672-634: The nickname "City of Caves". In 1985, the Chapada Diamantina National Park was created with its headquarters in Palmeiras . Chapada Diamantina is an erosional landform in the state of Bahia, Brazil . The Chapada Diamantina runs from North to South in the middle of Bahia and is an extension of the Espinhaço Range System . The rocks in the system date back to Pangaea and erosion of the formation began in

700-690: The northeast, and Palmeiras ( 12°31′S 41°35′W  /  12.517°S 41.583°W  / -12.517; -41.583 ) in the northwest. This region is named the Serra do Sincorá Ridge. However, the city of Ibicoara , near the southern limits of Chapada Diamantina, is also becoming important. The Sincorá Ridge is North–South oriented and has a length of 160 km and 20 to 30 km of width. It has huge canyons with rivers of brownish waters and several waterfalls. The high altitude grasslands are known locally as Gerais . The trails were once used by miners in their search for diamonds. From Lençóis, one of

728-526: The same area. However, there is evidence that life could have evolved over 4.280 billion years ago. There is a fairly solid record of bacterial life throughout the remainder (Proterozoic Eon) of the Precambrian. Complex multicellular organisms may have appeared as early as 2100 Ma. However, the interpretation of ancient fossils is problematic, and "... some definitions of multicellularity encompass everything from simple bacterial colonies to badgers." Other possible early complex multicellular organisms include

756-482: Was lacking in free oxygen . There is, however, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism . This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis , sometimes called

784-852: Was mud 551 million years ago. The RNA world hypothesis asserts that RNA evolved before coded proteins and DNA genomes. During the Hadean Eon (4,567–4,031 Ma) abundant geothermal microenvironments were present that may have had the potential to support the synthesis and replication of RNA and thus possibly the evolution of a primitive life form. It was shown that porous rock systems comprising heated air-water interfaces could allow ribozyme - catalyzed RNA replication of sense and antisense strands that could be followed by strand-dissociation, thus enabling combined synthesis, release and folding of active ribozymes. This primitive RNA replicative system also may have been able to undergo template strand switching during replication ( genetic recombination ) as

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