The Sabana Formation ( es, Formación Sabana, Q1_sa, QTs) is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

of the

Bogotá savanna The Bogotá savanna is a montane savanna, located in the southwestern part of the Altiplano Cundiboyacense in the center of Colombia. The Bogotá savanna has an extent of and an average altitude of . The savanna is situated in the Eastern Ra ...

Altiplano Cundiboyacense The Altiplano Cundiboyacense () is a high plateau located in the Eastern Cordillera of the Colombian Andes covering parts of the departments of Cundinamarca and Boyacá. The altiplano corresponds to the ancient territory of the Muisca. The Alt ...

Eastern Ranges The Eastern Ranges is an Australian rules football team in the NAB League, the Victorian statewide under-18s competition. The club is a founding member of the competition (1992) and has produced several players for the Australian Football Le ...

of the Colombian

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

. The formation consists mainly of

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

s with at the edges of the Bogotá savanna lignites and

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

s. The Sabana Formation dates to the Quaternary period; Middle to Late Pleistocene epoch, and has a maximum thickness of , varying greatly across the savanna. It is the uppermost formation of the

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

and fluvio-glacial sediments of

paleolake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

Humboldt Humboldt may refer to: People * Alexander von Humboldt, German natural scientist, brother of Wilhelm von Humboldt * Wilhelm von Humboldt, German linguist, philosopher, and diplomat, brother of Alexander von Humboldt Fictional characters * ...

, that existed at the edge of the Eastern Hills until the latest Pleistocene. The uppermost sediments of the Sabana Formation were deposited during the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eu ...

, a time when the first humans populated the Bogotá savanna. These hunter-gatherers used the bones of the still extant Pleistocene megafauna as '' Haplomastodon waringi'', '' Cuvieronius hyodon'' and '' Equus amerhippus lasallei'', of which fossils have been found in the Sabana Formation. Knowledge about the formation has been provided by geologists Alberto Guerrero,

Thomas van der Hammen Thomas van der Hammen (Schiedam, Netherlands, 27 September 1924 - Chía, Colombia, 12 March 2010) was a Dutch palaeontologist, botanist and geologist. He had published more than 160 works in five languages.Bogotá savanna The Bogotá savanna is a montane savanna, located in the southwestern part of the Altiplano Cundiboyacense in the center of Colombia. The Bogotá savanna has an extent of and an average altitude of . The savanna is situated in the Eastern Ra ...

(''Sabana de Bogotá'') by Hubach in 1957, further described by Van der Hammen in 1973,Acosta & Garay, 2002, p.65 Guerrero (1992, 1993, 1996) and by Helmens and Van der Hammen in 1995.Montoya & Reyes, 2005, p.72Guerrero, 1992, p.6Guerrero, 1996, p.3

Regional setting

The Bogotá savanna is a slightly undulated montane savanna in the southwestern part of the

, a high plateau in the Eastern Ranges of the Colombian Andes. The Altiplano was formed during the latest stage of Andean uplift in the Plio-

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

, exposing rocks of mainly

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Paleogene The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of ...

ages at surface. A small massif of

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

age is present in the northern part of the Altiplano; the Floresta Massif around Floresta comprising the fossiliferous formations Floresta and Cuche. During the Mesozoic, the central part of Colombia was a rift basin to the west of the

Guyana Shield The Guiana Shield (french: Plateau des Guyanes, Bouclier guyanais; nl, Hoogland van Guyana, Guianaschild; pt, Planalto das Guianas, Escudo das Guianas; es, Escudo guayanés) is one of the three cratons of the South American Plate. It is a 1 ...

, where series of marine platform deposits were deposited. The proto-Caribbean, the result of the break-up of

Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million ...

, formed a long seaway into the

South American Plate The South American Plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African Plate, with which it forms the southern part of the Mi ...

, up to Bolivia. During the Late Cretaceous, the Western and Central Ranges of the Colombian Andes began rising, while the Eastern Ranges was still absent. The main phase of tectonic uplift of the Eastern Ranges commenced in the Middle Miocene, marked by a change in paleocurrents of the fluvial deposits of the Honda Group, the most fossiliferous stratigraphic unit of Colombia. Subduction of the Nazca Plate underneath western South America and the resulting compression in the continent created reversal of former extensional faults of the Mesozoic rift basin in the Eastern Ranges. A series of

fold and thrust belt A fold and thrust belt (FTB) is a series of mountainous foothills adjacent to an orogenic belt, which forms due to contractional tectonics. Fold and thrust belts commonly form in the forelands adjacent to major orogens as deformation propagates ...

s, oriented in a north–south to northeast–southwest sense, were formed in the Eastern Andes, uplifting the former marine strata and creating a high plateau between the western and eastern fronts; the Altiplano Cundiboyacense. The tectonic movements of this Andean orogenic phase are reflected in Upper Miocene units as the

Marichuela Formation The Marichuela Formation ( es, Formación Marichuela, N1m) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of coarse to very coarse conglomerates. The Ma ...

, underlying the Pliocene and Pleistocene sediments of which the Sabana Formation represents the final chapter.

Description

Lithologies

The Sabana Formation consists mainly of horizontally bedded little consolidated grey and greenish

s with lignite and

diatomite Diatomaceous earth (), diatomite (), or kieselgur/kieselguhr is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine white to off-white powder. It has a particle size ranging from more than 3 μm to les ...

s, and fine to coarse

s at the edges of the Bogotá savanna.Guerrero, 1996, p.4 Numerous

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

deposits are noted in the Sabana Formation. Organic material is preserved in black soils and silts form the terraces of the central part of the savanna. The volcanic ash had as provenance area the

Central Ranges Central Ranges (code CER) is an Australian bioregion, with an area of 101,640.44 square kilometres (39,244 sq mi) spreading across two states and one territory: South Australia, Western Australia, and the Northern Territory.Boyacá (

Paipa–Iza volcanic complex The Paipa–Iza volcanic complex is a volcanic field of Late Pliocene to Early Pleistocene age on the Altiplano Cundiboyacense in the Eastern Ranges of the Colombian Andes. It is the northernmost volcanic complex of the Andean Volcanic Belt wit ...

). The diatomites are associated with the ash layers, a common feature in the geological record.Guerrero, 1996, p.5

Stratigraphy

The Sabana Formation in some areas conformably overlies the Subachoque Formation, in other parts unconformably the

Tilatá Formation The Tilatá Formation ( es, Formación Tilatá, N1t, Tpt) is a geological formation of the Bogotá savanna, Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The formation consists of coarse to very coarse conglomerates and sands ...

, and is overlain by the

alluvium Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

of the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

, with the southeasternmost area of the savanna covered and intercalated by the fluvio-glacial deposits of the Tunjuelo Formation. The formation is subdivided into six units of alternating shales and fine sandstones. The age has been estimated to be Middle to Late Pleistocene, based on

fission track Ion tracks are damage-trails created by swift heavy ions penetrating through solids, which may be sufficiently-contiguous for chemical etching in a variety of crystalline, glassy, and/or polymeric solids. They are associated with cylindrical d ...

analysis and

radiocarbon 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 de ...

. The Sabana Formation is time equivalent with the

Soatá Soatá is a town and municipality in Boyacá Department, Colombia. Soatá is located on the western slopes of the Cordillera Oriental mountain range, at the northeast end of the Department of Boyacá. It is the capital of the Northern Boyacá P ...

(upper Sabana),Villarroel et al., 2001, p.84 and Sogamoso Formations of the northern Altiplano,Guerrero, 1993, p.7 and the upper part of the Guayabo Formation of the

Llanos Basin The Llanos Basin ( es, Cuenca Llanos) or Eastern Llanos Basin ( es, Cuenca de los Llanos Orientales) is a major sedimentary basin of in northeastern Colombia. The onshore foreland on Mesozoic rift basin covers the departments of Arauca, Casan ...

.Guerrero, 1993, p.9

Depositional environment

The

depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will b ...

has been interpreted as

( Lake Humboldt) and fluvio-deltaic, with a near-continuous deposition since the

Late Pliocene Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effe ...

. The Sabana Formation represents the uppermost unit of the lacustrine deposition of Lake Humboldt. At the edges of the lake, numerous deltas of fluvio-glacial origin were present, reflected in the coarser sediments. During periods of stormy climate around the lake, coarser sediments were transported to the interior of the lake. The depositional cycles were geologically speaking fast and the water level of the lake fluctuated greatly during its history. Furthermore, the local tectonic activity of the Bogotá savanna, related to movements of the

Bogotá Fault The Bogotá Fault ( es, Falla de Bogotá) is a major inactive slightly dextral oblique thrust fault in the department of Cundinamarca in central Colombia. The fault has a total length of , while other authors designate a length of , and runs along ...

, influenced the depositional cycles. The middle unit of the formation shows a drying out of the lake and subaerial erosional surfaces.Guerrero, 1996, p.10 The upper part of the Sabana sequence is characterised by fluvial deposits around a retreating Lake Humboldt, estimated at an age of around 30,000 years BP. The glacial origin was predominantly the

Sumapaz Páramo Sumapaz Páramo (Spanish: ''Páramo de Sumapaz'' - meaning "Utterly peaceful moorland" ) is a large páramo ecosystem located in the Altiplano Cundiboyacense mountain range, considered the largest páramo ecosystem in the world. It was d ...

to the south of the Bogotá savanna, with minor snow-capped peaks in the Eastern Hills of Bogotá.Hoyos et al., 2015, p.265 Present-day, the lakes of Fúquene, Herrera and

Suesca Suesca is a town and municipality in the Almeidas Province, part of the department of Cundinamarca, Colombia. It is located on the Altiplano Cundiboyacense, north of the capital Bogotá. Suesca forms the northern edge of the Bogotá savanna and ...

are remnants of Lake Humboldt, as well as the many

wetlands of Bogotá Wetlands of Bogotá, Colombia are important areas of the capital city, and their development has become increasingly important for the area north of the Andes. A reserve for fauna and flora, the wetlands provide for the preservation and reproduct ...

Paleoecology

The Sabana Formation was deposited during the Pleistocene glaciations and interglacials ("

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gre ...

s"). The fluctuations in climate in the Eastern Colombian Andes have been studied around Lake Fúquene at an altitude of , to the north of the Bogotá savanna. During the

of the Pleistocene, the paleoecology of the region varied drastically, marking movements of the upper

tree line The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowp ...

and the types of vegetation. Pollen analysis shows that

páramo Páramo () can refer to a variety of alpine tundra ecosystems located in the Andes Mountain Range, South America. Some ecologists describe the páramo broadly as "all high, tropical, montane vegetation above the continuous timberline". A narrowe ...

vegetation was abundant from 30 ka to 17,500 years ago, with an increase in Andean forest frequency dated at 15.6 ka. Between 13,000 and 11,000 years BP, a decrease in Andean forest percentage is observed, indicative of a colder climate than before. This period has been named the Fúquene stadial. The stadial is followed by an interstadial ( Guantivá), with an increase in lake levels of Lake Fúquene.Urrego et al., 2016, p.703 The wetter periods of the interstadial covered earlier paleotopography with humic sediments.Scott & Meyers, 1994, p.390 During the last phase of deposition of the Sabana Formation, the Bogotá savanna was surrounded by populations of

Pleistocene megafauna Pleistocene megafauna is the set of large animals that lived on Earth during the Pleistocene epoch. Pleistocene megafauna became extinct during the Quaternary extinction event resulting in substantial changes to ecosystems globally. The role of hu ...

. Fossils of the

ground sloth Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Cari ...

s ''

Megatherium ''Megatherium'' ( ; from Greek () 'great' + () 'beast') is an extinct genus of ground sloths endemic to South America that lived from the Early Pliocene through the end of the Pleistocene. It is best known for the elephant-sized type species ...

'' and ''

Eremotherium ''Eremotherium'' (from Greek for "steppe" or "desert beast": ἔρημος "steppe or desert" and θηρίον "beast") is an extinct genus of giant ground sloth, in the family Megatheriidae, the largest and most heavily built family of sloths. ' ...

'' have been uncovered from Quipile,De Porta, 1961, p.52Bürgl, 1956 and

Fusagasugá Fusagasugá (; ) or Fusa is a town and municipality in the department of Cundinamarca, in central Colombia. It is located in the warm valley between the rivers Cuja and Panches, a central region of the Andes Mountains in South America. The muni ...

and Tocaima respectively, '' Haplomastodon waringii'' from Tocaima and Pubenza, accompanied by shells of '' Neocylotus cf. cingulatus'', to the west of the savanna, and '' Cuvieronius hyodon'' and '' Equus amerhippus lasallei'' from the Sabana Formation at

Tibitó Tibitó is the second-oldest dated archaeological site on the Altiplano Cundiboyacense, Colombia.Magdalena River The Magdalena River ( es, Río Magdalena, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much o ...

to the Eastern Ranges.Correal Urrego, 1993, p.4 Analysis of the fluorine in a fossil molar of a

gomphothere Gomphotheres are any members of the diverse, extinct taxonomic family Gomphotheriidae. Gomphotheres were elephant-like proboscideans, but do not belong to the family Elephantidae. They were widespread across Afro-Eurasia and North America dur ...

, found in the Sabana Formation at Mosquera, provided an age between the last interglacial and the first stage of the last glacial of the Last Glacial Maximum.Hammen, 1986, p.29 The fossils of Pubenza and Tibitó were dated at 16,300 ± 150 and 11,740 ± 110 years BP respectively.Hammen, 1986, p.30 Researchers at the Universidade Federal do Estado do Rio de Janeiro, UNIRIO propose that all gomphotheres found in Colombia should be reassigned to a single species; '' Notiomastodon platensis''.Mothé et al., 2016aMothé et al., 2016bMothé & Avilla, 2015Mothé et al., 2012 At the latest age of Tibitó, a páramo ecosystem was dominant.Cooke, 1988, p.180 File:Megatherium_NT_small.jpg, ''

'' File:Cuvieronius.jpg, ''

Cuvieronius ''Cuvieronius'' is an extinct New World genus of gomphothere, named after the French naturalist Georges Cuvier. Alive, specimens typically stood about tall at the shoulder, weighed about and would have superficially resembled a modern elephant ...

'' File:Caballo_sudamericano_(Parque_chuyaca_-_Osorno).jpg, '' Equus amerhippus lasallei''

Human settlement

The latest sedimentation phase of the Sabana Formation, evidenced by the sites

El Abra El Abra is the name given to an extensive archeological site, located in the valley of the same name. El Abra is situated in the east of the municipality Zipaquirá extending to the westernmost part of Tocancipá in the department of Cundinamarc ...

Tibitó Tibitó is the second-oldest dated archaeological site on the Altiplano Cundiboyacense, Colombia.Tequendama Tequendama is a preceramic and ceramic archaeological site located southeast of Soacha, Cundinamarca, Colombia, a couple of kilometers east of Tequendama Falls. It consists of multiple evidences of late Pleistocene to middle Holocene popula ...

, was accompanied by the first confirmed human settlement in Colombia. Around 12,500 years BP, groups of hunter-gatherers populated the rock shelters surrounding the retreating Lake Humboldt. The people of the area hunted the still extant Pleistocene species, and used their remains for the construction of primitive settlements, as bone tools and the skins as clothing. At this stage, the timber line was lower than today.Zonneveld, 1968, p.205 During the Holocene, the inhabitants of the Bogotá savanna gradually moved away from the rock shelters as permanent settlements in favour of more open area locations, as

Checua Checua is a preceramic open area archaeological site in Nemocón, Cundinamarca, Colombia. The site is located north of the town centre.Gómez Mejía, 2012, p.146 At Checua, thousands of stone and bone tools, stone flakes and human remains have ...

and

Aguazuque Aguazuque is a pre-Columbian archaeological site located in the western part of the municipality Soacha, close to the municipalities Mosquera and San Antonio del Tequendama in Cundinamarca, Colombia. It exists of evidences of human settlement ...

. Around 5000 years BP,

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peop ...

became a more dominant phenomenon and the fertile clays mixed with volcanic ash of the Sabana Formation, combined with the bimodal pattern of seasonal precipitation made the Bogotá savanna an ideal area for growing crops.

Pottery Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and po ...

was used in the

Herrera Period The Herrera Period is a phase in the history of Colombia. It is part of the Andean preceramic and ceramic, time equivalent of the North American pre-Columbian formative and classic stages and age dated by various archaeologists. The Herrera ...

, from around 2800 years BP onwards, and the sediments of the Sabana Formation were used for various styles of ceramics, grouped by

researchers Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness t ...

based on the colour of the original clays. The northern settlement of

was an important ceramic producing centre for the people. An advanced civilisation developed in the first and second millennia CE, leading to the

Muisca Confederation The Muisca Confederation was a loose confederation of different Muisca rulers (''zaques'', ''zipas'', ''iraca'', and ''tundama'') in the central Andes, Andean highlands of present-day Colombia before the Spanish conquest of the Americas, Spanish ...

, a loose collection of ''

cacique A ''cacique'' (Latin American ; ; feminine form: ''cacica'') was a tribal chieftain of the Taíno people, the indigenous inhabitants at European contact of the Bahamas, the Greater Antilles, and the northern Lesser Antilles. The term is a ...

s''. The southern Muisca area was centered around the Bogotá savanna with as main settlement

Bacatá Bacatá is the name given to the main settlement of the Muisca Confederation on the Bogotá savanna. It mostly refers to an area, rather than an individual village, although the name is also found in texts referring to the modern settlement of ...

in the middle of the savanna, the namesake of the current capital of Colombia,

Bogotá Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish period and between 1991 and 2000, is the capital city of Colombia, and one of the largest ...

.Gómez Londoño, 2005, p.281 With the expansion in the late colonial and early republican era of the Colombian capital to the west and north of the city, the unconsolidated finer sediments of the Sabana Formation became more and more the foundation for construction, leading to problems due to the differential compaction of the sandy and more clay-rich strata.Por qué se hunde la Sabana de Bogotá
- El Tiempo

Outcrops

The Sabana Formation is found at its

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

in the Funza II well, and covering most of the Bogotá savanna. The newer parts of Bogotá, especially the neighbourhoods north of the Avenida Chile (Calle 72) in

Chapinero Chapinero is the 2nd locality of Bogotá, capital of Colombia. It is located in the north of the city and is one of the more affluent districts of the city. This district is mostly inhabited by upper class residents. The boundaries are Calle 39 ...

and west of the Autopista Norte (Avenida 30), rest upon the Sabana Formation, where the unconsolidated shales cause frequent fissures in the roads constructed in the Colombian capital. The southeastern part of Bogotá, including the historic centre, rests upon the more competent Tunjuelo Formation.

Regional correlations

Notes

References

Bibliography

Geology

* * * * *

Paleoecology and history

* * * * * * * * * * * * * * *

= Proposed reclassification of gomphotheres

= * * * *

Maps

* * * {{Paleontology in Colombia, state=expanded Geologic formations of Colombia Pleistocene Colombia Shale formations Lacustrine deposits Fossiliferous stratigraphic units of South America Paleontology in Colombia Formations Geography of Cundinamarca Department Geography of Bogotá