Maranon River

The Marañón River is a river that flows entirely in Peruvian territory, which at its confluence with the Ucayali River forms the Amazon River. Its furthest source in its origin, relative to its mouth, is at 4600 m s. no. m. (meters above sea level) at the foot of Nevado Yapura (also called Cerro Caudalosa), whose summit is 5480 m high in the Raura mountain range, (Lauricocha province, Huánuco Region). Further north, in the Huayllay mountain range, there is a second important source of the Marañón: the sources of the Carhuacocha and Janca rivers, which will form the Nupe river, which when it joins the Lauricocha river will change its name to Marañón.

The length of the Marañón River is 1,707 km to its confluence with the Ucayali River near Nauta (Loreto), at 89 m s. no. m.. This length is referential since in the Amazonian plain the meanders of the river vary according to the floods and the emptying.

The catchment area of the Marañón river is 363,432 km² of which 297,038 (that is, 82%) are in Peru. The remaining 18% is in Ecuador.

According to Agustín de Zárate in his book History of the discovery and conquest of the province of Peru from 1555, its name is due to the Spanish explorer who discovered it.

Initial course

Originally, in the Raura mountain range, the Marañón is a small watercourse called Jayco. It crosses a series of small lagoons, which are followed by the Puyhuancocha, Caballococha, Anaspampa, Tinquicocha, Chuspi, and Patarcocha lagoons, after which it passes less than 100 m from the small C.P. San Miguel de Cauri, then continue to the Taulicocha and Lauricocha lagoons, from which the river with the same name comes out. From that point its route changes to the north, passing through the towns of Cauri, Jesús and Jivia. The Raura mine, located at the headwaters of the river, is a major source of pollution.

The confluence of the Nupe and Lauricocha rivers form the Marañón River. View from Mount Gongui.

At the foot of the plateau on which the city of Rondos sits and at the foot of Cerro Gongui, it meets the Nupe River and from there it is called Marañón. Three of the districts of the province of Lauricocha are located there which are Rondos, Jivia, which ends at the Gongui hill, and San Francisco de Asís, at the foot of the Talapunta hill.

Defiladero del nascent Marañón River.

From that point on, the banks of the rising Marañón alternate sandy beaches and gorges with almost vertical walls. Passing at the foot of the plateau where the city of Huarín is located, it heads northeast, entering the province of Yarowilca. After receiving the Llicllatambo stream on its east bank, it heads northwest.

Entering the province of Dos de Mayo, near the town of Tingo Chico, the Marañón receives the Vizcarra River on its left bank.

Further north, in the province of Huamalíes, it forms a deep canyon with a maximum drop of almost 1,500 m between the tops of the mountains on both sides and the watercourse. Near the town of Nuevas Flores is the Marañón hydroelectric plant with 18.4 MW (megawatts) of installed power.

Intermediate course and section of the pongos

View of the Marañón River from Urpish.

The river continues north in Huánuco, through the districts of Chavín de Pariarca, Tantamayo and Jircán, passing through the town of Urpish. There it takes the northwest direction, acting as a natural limit between the Áncash and Huánuco regions. In this part the width of the riverbed narrows and the unevenness is accentuated even more. On its west bank, corresponding to the district of Rapayán, in the province of Huari (Áncash), the walls of the canyon reach very steep slopes, of almost 90°, so that the west bank of the river and the peaks are almost on the same vertical. This feature extends to its confluence with the Contan River, which comes from its left bank.

In contrast, on its eastern margin, which is the western flank of the Central Cordillera of the Northern Peruvian Andes and corresponds to the districts of Jircán and Arancay (Huánuco), its slope is slightly gentler, which favors the settlement of populated centers and agricultural activities.

Marañón River seen from the hill of Yarcan, between the provinces of Antonio Raimondi and Huacaybamba, of the departments of Áncash and Huánuco respectively.

Following the same northwest course, it receives the waters of the Puchka River on its southwest bank, at an altitude of 2,117 m above sea level. Between the provinces of Antonio Raimondi and Huacaybamba, Ancashina and Huanuqueña respectively, the Marañón River forms a deep and wide valley running between the Western Chain and the Central Chain of the Andes Mountains. Then, on its left bank, it first receives the waters of the Yanamayo River, which has its sources in the Alpamayo, Chacraraju and Huascarán snow-capped mountains, and then those of the Rúpac River. In that place there is one of the rare bridges that cross the Marañón, on the road that connects the port of Chimbote with Tocache Nuevo, in the mountain range. It is the site of the 314 MW Yaku hydroelectric project.

Some 130 km further north, when it marks the border between La Libertad and Áncash, the Marañón is partially cut by the Wasson Landslide, named by kayakers in honor of John Wasson. He and three companions descended the river in 1977, in kayaks and a raft, from Rondos to Nazareth. The landslide was a consequence of the 1970 earthquake and forms class V and VI rapids, spectacular but impassable by boats and kayaks, which must be carried or towed from the shore.

The orographic characteristic in this section is that of a deep canyon that erodes the Andean plateau with unevenness between the summits of the edges and the water line that vary between 2,990 and 3,130 m. The rugged and narrow nature of this route forms a spectacular landscape where agricultural activities are minimal. However, in the afternoons, the inhabitants of the towns on the summits descend several hundred meters to fish in the river.

Further north and within the department of La Libertad, the river separates the provinces of Santiago de Chuco and Sánchez Carrión, on its western bank, from the provinces of Bolívar and Pataz. There, in Chagual, is the only airfield in the region and the highway from Trujillo to Pataz and Parcoy crosses the river on a bridge that leads to the productive Poderosa, Horizonte and Retamas gold mines. The residues left there by the mining corporations are exploited by informal miners. In Pataz is the Pías lagoon and begins the path that descends to the Río Abiseo national park, which contains the remarkable ruins of Gran Pajatén, from the Chachapoyas civilization.

Some 45 km further north is the town of Calemar where the writer Ciro Alegría, who was born on the neighboring Marcabal Grande farm, was inspired by the life of the river rafters for his novel The Golden Serpent , a classic of Peruvian literature. In Calemar there is a bridge over the Marañón on the road to Cajabamba. At 1,142 m high it already has a warm climate, but there are very few cases of malaria and dengue. Rather, your medical post should treat, from time to time, snake bites.

From here the Marañón separates the Cajamarca and Amazonas regions and forms a deep and spectacular canyon. It is about 260 km long, with a 3,000 m drop between the highest peaks on both sides and the river, and is perhaps one of the most beautiful in the world. Its banks are covered with tropical vegetation and there are coconut palms cultivated by the few inhabitants. There are two hydroelectric projects here, Rio Grande 1 (600 MW) and Rio Grande 2 (150 MW). It receives the Crisnejas River on its left bank, which also descends cutting a deep canyon. In the town of Balsas, at an altitude of 860 m, a steel bridge crosses the Marañón carrying the highway from Trujillo, an important commercial artery that descends vertiginously from Cajamarca (2,729 m) and then climbs the canyon towards Chachapoyas (2,021 m).).

Farther north there are a few hamlets that can only be reached by mule. They have four oroyas (cables to cross people and mules) over 170 km in length. They are called Mendán, Tupén and Chucen (total population, approximately 1,500 people). Electricity only arrived there in 2015. The predominant crop is coca, which is collected by merchants who regularly come with their mules to those valleys populated by giant cacti. On the Cajamarca side (Celendín province) cocoa of magnificent quality is produced. A band that crosses South America from east to west, from the Guianas to northern Peru and southern Ecuador is the area of origin of cacao (Theobroma cacao) and around the Marañón many different cultivars are found. In this section of a river with narrow gorges and many rapids, are the controversial and suspended hydroelectric projects Chadín 2 (650 MW), south of Chucen, and Veracruz (730 MW), in an area of sparsely populated forests. The latter has been formally abandoned by its concessionaire, the ENEL company.

The river flows out of the canyon in Cumba into the wide valley of the Chamaya River covered with rice crops that also favor the proliferation of mosquitoes. There is another bridge there, in Corral Quemado, the one on the highway from Paita and Chiclayo to Tarapoto and the port of Yurimaguas, over the Huallaga River. Modernized and fully paved over a length of 955 km, it has been named Interoceánica Norte (IIRSA Norte), since it is one of the links in the road-river transport system that connects the port of Paita, in the Pacific Ocean, with the port of Belém do Pará on the Atlantic Ocean. It was built by the Brazilian company Odebrecht and is part of a huge corruption scandal in which four former Peruvian presidents were involved: Alejandro Toledo, Ollanta Humala, Pedro Pablo Kuczynski and Alan García. The latter committed suicide.

From here the river is much wider and both banks are populated. In the afternoons there can be very violent winds on the river, coming from the north. There are two medium-sized cities nearby. On the west side is Jaén, which was founded by the Spanish in 1549. It has 106,000 inhabitants and a river port, Bellavista, which, since the 17th century XVII was used by the Jesuit missionaries who came from Quito who wanted to evangelize the jungle tribes of Marañón. On the east side is Bagua Grande, a commercial city of 85,000 inhabitants. A few km further north it receives two large rivers: the Utcubamba on its right bank and the Chinchipe on its left bank. At this confluence the river opens into a large lagoon populated by thousands of waterfowl.

Here the Marañón begins to cross the eastern branch of the Andes Mountains. It is the beginning of the region of the pongos, from the Quechua punku, door. These are narrowings of the river bed that form violent rapids. The first pongo is that of Rentema, whose banks are covered with fossils of Cretaceous marine fauna. On one of the slopes of the pongo, in Cerro Fidillas, the remains of a titanosaur from 68 million years ago have been found, it is the largest dinosaur that has been found in Peru so far. At the foot of the hill there are hot springs. At the exit of the pongo, in a ravine, on its right bank, is the small hydroelectric power station of El Muyo (5.4 MW). This is the beginning of the Amazon jungle and the territory of the Awajún ethnic group, with the native community of Tutumberos. An authorization from them is required to transit through the river. Just to the north, at the elevation of 350 m s. no. m., studies have been made for the Lorena hydroelectric project (300 MW). If a part of Tutumberos is carried out, it would be flooded. To the north of Tutumberos are the Numpatkaim, Suspiro, Yamakaintsa, Shaime and Lorocache pongos, which can be dangerous for a boat during the flood season.

Throughout its upper and middle courses, the Marañón forms the main inter-Andean valley of northern Peru, between the Western and Eastern Chains of the Andes.

Further north are Yupicusa, the largest Awajún town on this stretch, the mouth of the great Chiriaco River, and Imacita, a small commercial port where the river is already navigable by passenger boats that can go as far as Iquitos. Imacita was originally a service center for a military colonization program on the Ecuadorian border that was abandoned. It already appears on maps from the 18th century) and Huaracayo.

It receives on its left bank the Comaina River that comes from the Cordillera del Cóndor, bordering Ecuador, and reaches Santa María de Nieva (21,000 inhabitants). It was founded in 1555 by Jerónimo de Loyola, who gave it that name in honor of the then viceroy Conde de Nieva.

Its average annual temperature is 26 °C. Santa María de Nieva is an important branch of the Apostolic Vicariate of San Francisco Javier, which is entrusted to the Jesuits. The Vicariate has a network of agents in the vast jungle territories north of the Marañón River and therefore is an excellent source of information on this area where the State is very little represented, basically only by small military garrisons near the border with Ecuador.. A person wishing to visit these territories requires prior authorization from the indigenous populations. In this section of the river there are gold pans, with the consequent arrival of illegal miners and mercury contamination, which has given rise to clashes between miners and indigenous people.

Downstream it receives on its left bank the mighty Santiago River, a great Amazonian river that comes from Ecuador. At its mouth is the Teniente Pinglo military settlement. Then find the last and largest pongo: the 12 km long Pongo de Manseriche. There the river crosses the last branch of the Andes, the Kampankis mountain range, in which the mountains rise up to 1,100 m. The Marañón narrows from about 250 to 400 m wide to only 35 m. The pongo in its narrowest part is about 4 km long. It is at 212 m s. no. m. In the rainy season, a large and turbulent flow rushes there, which makes it dangerous for small boats. For a long time there has been speculation about the possible construction of a hydroelectric plant in this place. Theoretically it could have 4,500 MW of installed capacity but it would flood 5,470 km², including Ecuadorian territory, which makes it unfeasible.

Final Course

At the exit of the pongo is the semi-abandoned town of Borja, founded in 1619 to be the spearhead of the missionaries and conquerors of the province of Maynas, who came from Loja and Quito. After the expulsion of the Jesuits from Peru by Carlos III, in 1767, it was destroyed by the Huambisas (wampis) and passed into oblivion.

Here the Marañón is crossed by the oil pipeline that comes from Andoas, near the Ecuadorian border, and which will connect near there, at Station No. 5, with the one that comes from the east, from Pavayacu and Trompeteros. It is the beginning of the Loreto Region and of the great Amazonian plain that extends to the Atlantic Ocean. From here the Marañón is a multi-channel river, with large meanders. and its bed is sandy, clayey and silty. On its banks there are lakes and tipishcas, lagoons originated by the breakage of a meander when the river deviates laterally, and tahuampas or aguajales, permanently or seasonally flooded. They are biologically very rich areas. In times of flood, thousands of hectares along its course are flooded when the river level rises several meters. In May 2020, in Nauta, it was 8 m. higher than its September level. Millions of fish breed in those flooded areas and then migrate to many rivers in the Amazon basin. 73% of the wetlands in the Peruvian Amazon are located in the "Marañón wetland complex".

About 20 km away, on the right bank, is Saramiriza (2,000 inhabitants). It is the terminus of the highway that comes from Lima and Bagua. It would also be the future start of the controversial road project to Iquitos. This project is opposed by the indigenous communities for being destructive to the Amazon rainforest and wasteful.

From here, the Marañón will receive several large tributaries that will make it the river that contributes the most to the Amazon. On the left bank it receives the Morona river and then the Pastaza, both are born in the volcanic chains of the Ecuadorian Andes. Before the mouth of the Pastaza is San Lorenzo, capital of the Datem del Marañón province (16,000 inhabitants). It has an airfield and is the main urban center that serves the Awajún, Achuar, Candoshi and Kichwa ethnic groups from Pastaza, who live to the north of the Marañón, and the Shawi, Shiwilu (jeberos), Cocama and Cocamilla to the south of it.

Continuing to the east, it receives its largest tributary, the Huallaga, on its right bank, with an average annual discharge of 2,970 m³/s, measured in Chazuta, 470 km by river from the mouth of the Marañón. In the Huallaga is the port of Yurimaguas, terminus of the IIRSA Norte highway, already mentioned. There, important cargo and passenger traffic heading to Iquitos embarks on boats with a depth of more than 2 m. There is also Lagunas, a town that in the 17th and 18th centuries was an important missionary base for the Jesuits. Between the mouth of the Huallaga and Nauta, where the Amazon River begins, the most important tributaries that the Marañón receives on its left bank are the Nucuray, the Urituyacu, the Chambira and the Tigre. It has several small towns on its margins populated by settlers from the Sierra and Cocama-Cocamilla indigenous people. They grow rice, plantains and cassava in the várzeas, fertile silt lands left behind by the river's flooding. The Kukama community of San Pedro was affected in 2014 by an oil spill, product of the rupture of the oil pipeline, with serious impacts on the health of the population. The most important town is Santa Rita de Castilla, an Augustinian parish facing the mouth of the Samiria River.

On the right bank is the Pacaya-Samiria National Reserve with more than 2 million hectares and an extraordinary biodiversity. It is a wedge between the Ucayali and Marañón rivers, which when joined form the Amazon. Near that confluence is Nauta, a city of 34,000 inhabitants founded in 1830 and linked by road to Iquitos. It is a small river port whose boats serve many towns and tributaries of the Marañón and Ucayali.

The Marañón River is born 4600 m tall with the name of the river Lauricocha. By joining Nauta with the river Ucayali forms the Amazon.

Hydrology and geomorphology

The Marañón is a river of "white waters", that is to say, milky in color, due to its load of sediments originating in the Andes mountain range. It is a braided river, with many islands, but also with straight sections. In the flow measurement stations of Borja and San Regis (56 km by river from the confluence with the Ucayali, to form the Amazon) the flows have been verified, in cubic meters per second, recorded in the following table. For comparison, the Requena station on the Ucayali river has been added, which confirms that the river that contributes the most to the Amazon is the Marañón: At its confluence with the Ucayali, the seasonal amplitude of the river level can be from 10 to 20 m.

Water levels of the Marañón River at the Borja Station, 2017/2018 and 2018/2019 (Source: SENAMHI)

The historical rise of the Marañón River has been 32,000-33,000 m³/s. With the exacerbation of global warming, the frequency of extreme events: droughts, cold weather, and floods is increasing in the Amazon. In July 2011, at San Regis, for a flow of 18,923 m³/s, a maximum velocity of 1.65 m/s was recorded on the surface. The mouth of the Marañón is 1.7 km wide at its confluence with the Ucayali.

At the mouth of the Samiria river, a "black waters" river, where it joins the Marañón, 0.5 to 2.5 mg/liter of dissolved oxygen and a pH between 4.9 and 6.9 have been measured.

Variations in the morphology of the river in its Amazonian part can be seen on the Ríos Danzantes platform. been published by the Center for Water Research and Technology (CITA) of the University of Engineering and Technology of Lima (UTEC).

Sediments

Sediment transport in Amazonian rivers is maximized during a few heavy rain events and the frequency of these storms increases during ENSO (El Niño-La Niña) cycles. The Environmental Impact Study of the Chadín 2 hydroelectric project estimated that some 40.5 million tons of sediment a year would pass through the dam site, if there is no other dam upstream, of which 90% would be retained. The only other existing study of sediments on the Marañón has been for flows in the years 2000-2009, with high waters from November to June and maximum flows from April to May, has given the results of the following tables. In Borja, the concentrations of suspended sediments show regular values throughout the year but increase to more than four times the average in high waters. In San Regis the sediment peaks are 2 or 3 months before the maximum flood and 45% of the sediment volume is transported between May and June. The temporal variability is very large. The Peruvian Amazon basin exports approximately 629*10⁶ ±36% tons of suspended sediment per year and a flow of 36,000 m³/second. The Ucayali River exports the largest amount of sediments 61.2%. Marañón 30.4% and Napo 8.4%. The Marañón, Huallaga and Ucayali rivers transport 385*10⁶ ±55% tons/year.

Geology and soils

The fluvial system of the Amazon River has developed between the last 9.4 and 9 Ma (million years), after the Venezuelan mountain ranges rose and forced the north-flowing waters to flow towards the Ocean Atlantic. The western part of its fluvial system is the product of the uplift of the Andes mountain range.

The Andes began to rise during the Paleogene (66-34 Ma). This movement buckled the lithosphere of the South American plate creating the Andean foreland basin, which consisted of a series of tiered basins, cut by segments of older rock (arches). An unstable river network developed in this geodynamic landscape. During the Quaternary, the evolution of the landscape was controlled by glacioeustatic changes, whose effects can be felt up to the center of the continent. Lacustrine and fluvial sediments originating from the erosion of the Andes have been filling these subsidence basins. The current várzeas and the numerous associated lagoons are witnesses of ancient valleys that the sediments did not completely fill. The largest anticline in the region, the Arco del Moa (Serra do Divisor, Acre, Brazil), is a series of peaks that, upon emerging, forced the Ucayali, Huallaga, and Marañón rivers to run northward. Those rivers are rich in suspended sediments that are transported to the lowlands and then to the sea. The last uplift in the eastern Andes of Peru was 5-6 Ma ago.

The Andean orogeny comprises at least six separate compressional phases. One of them is the Inca Phase, which formed the Marañón thrust and fold belt in the Eocene, of which the Raura and Huayhuash mountain ranges are part. The Raura system is a set of Cretaceous limestone folds that have been uplifted at a later stage by the intrusion of plutonic rocks. The limestone that forms its high peaks, generally anticlines, have undergone some contact metamorphism due to the heat of the igneous rocks. Plutonic rocks are represented, for the most part, by granodiorites.

The Huayhuash mountain range was formed 50 to 70 million years ago. The elevation of the original seabed has been carved by glaciation and water erosion. The consolidated material that forms the mountain range is, above all, sedimentary rocks such as quartzite, limestone and slate, while the bases of the mountains are made up of granodiorite. The southwestern end of the chain is recent extrusive volcanic rock.

The Marañón basin is a transition between the Brazilian craton and the Andes mountain range. The upper Marañon valley runs in a southeast to northwest direction, in the Eastern Cordillera, on a surface of erosion that developed between 3,600 and 4000 m s. no. m. and that is modified and dissected by the intensive erosion of the rivers rejuvenated by the Andean uplift of the Paleogene and the Neogene. The valley is a rift whose relative subsidence resulted in the capture of part of the pre-existing drainage, exposing multiple stratigraphic units from the Precambrian metamorphic basement. In the area between Pataz and Parcoy, associated with the batholith, there are gold-bearing sulphide veins that have been intensively mined since ancient times.

The oldest exposed rocks in the Peruvian Andes are in the Cordillera Oriental and are the consequence of an uplift of the Marañón Arc/horst. They are up to 75 km wide and extend over a large part of the length of the Peruvian Andes. They are part of the Marañón Complex that originally formed as the Marañón Magmatic Arc, from the Cambrian to the Devonian. In the Pataz-Parcoy area over a length of 160 km, the continental margin of Gondwana is represented, in the Proto Andes, which was active mainly during the Paleozoic, 342-319 Ma ago.

In the Eastern Cordillera, the Marañón descends through narrow canyons and, after leaving it, crossing the Campanquiz mountain range, it reaches the last one: the Pongo de Manseriche. The Campanquiz mountain range would have begun to rise in the middle Miocene. Outcrops of Cretaceous through Neogene sequences are exposed in the Pongo de Manseriche on both flanks of the Kampankis (Campanquiz) anticline.

The Marañón in its lower part forms very sinuous channels that migrate continuously and has a lot of erosion on its banks. After its confluence with the Pastaza River, the north bank of the Marañón is made up of the Pastaza fan, formed by alluvium rich in pyroclastic origins from the volcanic chain of the Ecuadorian Andes. El Abanico is a mosaic of swamps dominated by palm trees, especially the aguaje (Mauritia flexuosa) and various types of forests.

The Marañón-Pastaza sub-basin is a vast area of modern degradation (60,000-70,000 km²) with extensive subsidence depressions and floodplains. Sediment deposition in this fluvio-lacustrine environment is a consequence of the uplift of the Arc of Iquitos. The interfluvial zone between the Marañón and the Ucayali is the so-called Ucamara Depression. Both rivers have migrated in the last 13,000 years, the Marañón 50 km to the north and the Ucayali 75 km to the southeast. Here is the Pacaya-Samiria National Reserve, made up of a mosaic of different vegetation patterns, which are defined by seasonal flood cycles.

In the Andean foreland basin, "terra firme" (non-flooded lands) are extremely variable due to their different sedimentation histories. The denudation of the ancient plains of the western Amazon and the intense wear caused by rains and temperature changes have gradually modified the soils, influencing the distribution patterns of the biota and creating extremely specialized habitats. The geochemistry of the sediments transported by the rivers and that are deposited in their floodplains bear the imprint of their origins and their source rocks. Your granules can tell your story.

Gold and oil

In the metallogenic zone of Pataz, Parcoy and Buldibuyo are some of the oldest and most productive gold mines in Peru. In 2019, the Poderosa, Retamas, Horizonte and Caravelí-La Estrella mines produced 20,072 kg of fine gold, that is, 17% of the total official production of Peru117 tons. In reality, due to illegal mining, not accounted for, production of the country is much higher. Unfortunately, the wealth extracted during more than a century of mining exploitation is not reflected in the standard of living of the population that suffers from poverty and deficient education, health and communication services.

Between the confluence with the Cenepa and the Santiago river there are also laundries, looking for alluvial gold that comes from the Cordillera del Cóndor. It is a source of conflict with the native communities, harmed by the contamination of the water with mercury.

The Marañón sedimentary basin is an oil zone with proven reserves of 254.1 million barrels of oil (MMSTB) and proven and probable reserves of 431.7 MMSTB. It consists of a system with Cretaceous source rock, known as the Chonta Formation, and another petroleum system with Jurassic source rock, known as the Pucará Formation. The main productive fields are located in the northern sector of the basin on the border with Ecuador. But multiple anticlines that have been investigated with various soundings have yielded dry wells.

In 2021, the oil concessions for exploitation, in the Marañón basin, add up to 1,125,000 hectares, with six companies, all foreign, with current exploitation contracts, with terms ranging up to 40 years. The oil extracted is mostly a heavy oil (°API 18, approximately). The PlusPetrol Norte company decided to abandon its concession in December 2020, but refuses to restore the sites affected by the multiple oil spills as a result of its work and those of the companies that preceded it, alleging that its contract does not oblige it to do so.. According to the Peruvian State, it is obliged to do so. In the Peruvian Amazon there are more than 1,500 sites contaminated by oil activity.

Along the Marañón River, from San José de Saramuro to El Milagro (Bagua), runs the North Peruvian Oil Pipeline that collects oil from the northern Amazon and takes it to Bayóvar, a port on the Pacific Ocean. It has two branches, the North of 16" and Section 1 (East-West) of 24" who come together at Pumping Station 5 in Sarameriza, the scene of frequent conflicts with the indigenous, caused by the many spills. Indigenous communities depend on clean water and a clean forest to survive.

High levels of lead have been detected in the blood of the Achuar, Kichwa and Kukama indigenous people living in the areas around oil blocks 8 and 192, located in the Marañón, Tigre, Corrientes and Pastaza river basins. Lead causes permanent neurological damage and affects the growth of children. The soils in these areas are contaminated with lead, barium, cadmium, hexavalent chromium, petrogenic hydrocarbons and others. Lead has entered organisms through food with fish and bush meat.

Ecosystems

From its sources in the Raura and Huayhuash mountain ranges to its confluence with the Ucayali, the Marañón basin traverses 16 major categories of ecosystems, as defined by the Peruvian Ministry of the Environment. North of the Marañón, in a great triangle limited to the west by the Cordillera del Cóndor, to the south by a line that crosses the middle of the Pastaza Fan and the Ucamara Depression reaching the confluence of the Amazon with the Yavarí and to the north by a line that contains the entire Putumayo basin would be one of the forest refuges of the end of the Pleistocene and post-Pleistocene, times of great dry periods, in which plants took refuge that would later colonize a large part of the Amazon basin.

Andean Zone

• Areas and glaciers: Over 4,500m. Crioturbated and discovered soils. Low and scattered vegetation with lichens, mosses, yarets, few grams, asteraceae, and padded plants. Glaciers include ice masses and rocky detrites. Global warming is rapidly causing its disappearance.
• Wet puncture Pajonal: High Andean pasture or ichu with herbaceous vegetation. In general dominated by robust species of poppy growth grams and often hard or pungent leaves, with a significantly different lower herbaceous stratum in which they are common low cespitous and breast-feeding biotypes as well as various forbias, mainly rhizomatous and rhizomatous hemicriptophytes, sub-phrutic scams and some gejophites. They're very affected by grazing.
• Bofedales: Hydromorphic ecosystem with evergreen herbaceous herbaceous vegetation, with almohadillado or cushion, from 0.1 to 0.5m, on permanently flooded or saturated soils of running water. Organic soils can be deep (turba).
• Andean high relict forest: Dominated by associations of queñua (Poylepis spp.) with trees up to 2m. Distributed in patches on rocky and broken slopes.
• Jalca: Ecosystem with herbaceous vegetation and humid arbustive, with intermediate climatic characteristics between wet puna and paraamo (more wet than puna and not as rainy or as covered with clouds as the paraamo). It has herbs of 1 to 1.5m mixed with bushes of 1 to 3m. It shares botanical species with puna and paraamo but also has gender endemisms Agrostis, Poa, Festuca, Arcytophyllum and others.
• Matorral arbustivo Andino: It has an altitude range between 1000 and 3800 m. n. m.. The vegetation is woody and arbusive of composition and variable structure and whose height does not exceed 4m. In the dry puna bush there are extensive areas of tola (Parastrephia quadrangularis... Baccharis and others. Typical vegetation between 2000 and 3500 m. n. m. includes Lupinus balianus (chuckles) Diplostephyum sp., Stage Dunalia, Hesperomeles sp. (manzanite) and woods like Oreopanax sp., Miconia sp. and Vallea stipularis. In the lower floor scrub, according to the aridity of the weather, the arbusive communities lose their foliage during the dry season. Common species are Jatropha sp(huanarpo), Ortopterigium huasango (huancoy) Carica candicans (sighs) Fourcroya andina (magüey) etc. There's arborescent porte succulents like Echinopsis pachanoi (San Pedro) Armatocereus sp. In range 2500 to 3800 m. n. m. for subhumid conditions the arbusive communities are deciduous and perennifolio-type with enough floristic diversity. Among the most common species there is Dodonaea viscosa (chamana), Kageneckia lanceolata (laughs) Tecoma sambucifolia (huaranhuay) Spartium junceum (retama), etc. Other frequent species are cactaceae Opuntia subulata (anjokishka) and scattered and low porte arboreal species Macracantha space (faique), Schinus molle (molle) and Caesalpine spinosa (tara).
• Interandino seasonal dry forest: Its altitude ranges from 500 to 2500 m. n. m. approximately. Dominated by deciduous arboreal communities, including in the lower stratum seasonal herbal species. Arboreal porte cactaceae are noticeable, abundant and mostly endemic. The dominant physiognomy is that of an open forest, on the slopes and at the bottom of the valley, with individuals up to 7 and 8 m.

Yunga area

• Yunga rainforest: Forest ecosystem located on the eastern side of the Andes, between 2500 and 3600 m. n. m.With very rough physiography. Forest with closed canopy with up to three strata. Dosel up to 15m with some 20m pop-up trees. High floristic and abundant epiphytes. The border with the puna pajonal is a dwarf forest of up to 2 to 3m high, formed by Ericaceae, Solanaceae, Asteraceae, Polemionaceae, Rosaceae, among others.
• Yunga mountain forest: On the eastern side of the Andes, between 1500 and 2500 m. n. m.with strong slopes. Closed canopy forest from 18 to 25 m high, with some emergent trees of 30 m and great floristic wealth. According to the orientation of the slope can be constantly covered with fog. Presence of abundant epiphytes, bromeliaceae and orchidaceae. Presence of arborescent ferns up to 10 m high and diameters up to 20 cm, mainly of the genus Cyathea.
• Basimonial forest of yunga: Non-white ecosystem, between 300 and 1,500m. Dosel closed up to 25m high, with some emergent trees up to 35m high. Floristic composition of transition between the low Amazon and the yunga with presence of epiphytes.

Rainforest area

• High hill forest: Amazon ecosystem, between 90 and 300 m. n. m. in unwashed terrain and with slopes ranging from moderate to steep. When the rains are deforested, they cause a strong erosion. They can be strongly disconnected. They have a dense sotobosque and the vegetation can present 3 and 4 strata, with domes up to 25 m high and emergent trees up to 35 m, with trees of lower height in the upper parts of the hills.
• Ground hill forest: Denso sotobosque, arboreal domes up to 25 to 30m and emerging individuals up to 35 m and above height.
• Non-inundible terrace forest: Firm land ecosystem (not flooded by the growing ones). Flat topography with ripples up to 20vm high. It includes old terraces in the process of erosion, often surrounded by low hill forests. It gives vegetation with trees up to 25 m high and emerging individuals over 30 m high. Palm trees are common. The drainage of the land is good to regular.
• Inundible alluvial forest: In flat land, it is flooded with the growing ones, which usually vary between 5 and 8 m high. Floods are seasonal but some areas are permanently flooded. The sotobosque is ralo and open and the forest can present 3 or 4 strata with a canopy up to 20 to 25 m high and emerging trees up to 30 m high. It encompasses heterogeneous groups of coastal vegetation and forested swamps that depend on the dynamics of the river. Characteristic trees are blind (Cecropiaceae), renacos (Ficus citrufolia), colored pungas (Pseudobombax munguba) capironas (Calycophyllum spruceanum) and ballins (Guazuma crinita).
• Bread of palm trees: They exist in alluvial plains and may be permanently or temporarily flooded. It has deep organic soils, with peat strata up to 1 metre. It has dense palm trees of water (Mauritia flexuosa), palm or chonta (Precatory cervix), bleach (Mauritiella aculeata) and other palm trees up to 25 and 30m high. accompanying species are Punctulace face, Marila laxiflora, Ficus spp. and Cecropia.
• Arbustive herbaceous swamp: Hydromorphic ecosystem dominated by gramines and cyperaceae, subject to seasonal floods. Organic soils more or less deep with peats, Herbazales 1.5 to 2 m, with some emerging bushes up to 5 m.

The seasonally dry tropical forest ecosystem

In the Marañón valley, in the Yunga zone, from 9°30'S to the confluence with the Chamaya river, there is an ecosystem of seasonally dry tropical forests that is unique in Peru. It is the richest basin in woody and endemic species among all the basins in Peru where this type of ecosystem is found. It contains mixed-type forests (thorny scrub and savannah), mixed with a predominance of cacti and riparian gallery forest.. They grow plants of the genera Acacia, Espostoa, Croton, Capparis Cnidosculus and Jatropha. There are species of flora such as Parkinsonia peruviana (palo verde), Cedrela kuelapensis (cedar), Clusia sp. (teaspoon) and Caesalpinia celendiniana.

Without a doubt, the Marañón Valley is one of the most important areas of endemism in Peru, with 12 species exclusive to the region and another 10 shared species.

There are practically no studies on its biodiversity, but the team that carried out the Environmental Impact Study of the Chadín 2 hydroelectric project (EIA) took several samples and studied a series of plots that indicate its richness. 17 endemic botanical species and 20 species in one or more threat categories were found, according to the criteria established by CITES and the Peruvian government.

From the ornithological point of view, the EIA found 79 species distributed in 29 families and 13 orders. Among them there are 27 species that are in some category of threat. 7 endemic bird species were found, indicators of environmental quality since their existence is linked to that of very precise biotopes. Unique endemic species in the world are the Inca brown-shouldered finch (Incaspiza laeta), the Cashew parakeet (Forpus xanthops) and the hummingbird Taphrolesbia griseiventris. The only ornithological study of the Marañón valley is a study of the Marañón-Alto Mayo bird conservation corridor.

In terms of insects, no species included in any category of protection was found, but endemic species of wasps and butterflies were found. In reptiles and amphibians, a significant number of endemic species was recorded, but few included in protection categories.

The EIA identified 27 species of mammals in the area, including the possibility of larger fauna such as the spectacled bear (Tremarctos ornatus) and the puma (Puma concolor). The existence of the river otter (Lontra longicaudis) is confirmed. Among them are 8 species categorized as in some state of threat (including the three mentioned above) and one endemic: the Osgood's rice paddy mouse (Eremoryzomys polius),

In the health posts along the river we have been told that there are sporadic bites from venomous snakes, apparently of the genus Bothrops (palm). Identified reptiles are the blind snake Anomalepis aspinosus, the snake Dipsas latifasciata, the dwarf boa Tropidophis taczanowskyi, the gecko Phyllodactylus interandinus and the lizard Tropidurus stolzmanni.

In the Amazon Region, in the districts of Balsas, Cocabamba, Ocumal, Pisuquia and Providencia, a 13,900-hectare Regional Conservation Area of Seasonally Dry Tropical Forests of Marañón has been created. In Celendín, Cajamarca, there was an attempt to constitute the Huacaybamba Regional Conservation Area, but it did not prosper.

The Pastaza Fan

The Priority Area for the Conservation of the Abanico del Pastaza y los Varillales del Bajo Morona is limited in its southern part by the Marañón river, by the watershed between the Santiago and Morona rivers, to the west, and by the mouth of the Pacayacu River to the east.

El Abanico is one of the largest tropical alluvial fans in the world and is a 38,000 km² wetland complex. It is formed by alluvium from the volcanoes of the Ecuadorian Andes, which have created "black lands" and it is a mosaic of ecosystems with vast swamps, different types of swampy vegetation, forests and palm groves, containing almost all types of wetlands found in the Amazon biomes. Such floodplains are breeding grounds for large populations of fish and essential for maintaining the ichthyological productivity of the Pastaza and Marañón basins. Its ichthyological diversity is much higher than that of the Pacaya-Samiria Nature Reserve.

The Fan peat fields cover about 35,600 km² (that is, one and a half times the extent of Israel) and contain 3,140 million tons of carbon. This value is uncertain and depends on variations in thickness and the density of peat deposits. A very particular ecosystem has been found with slender trees (10 to 25 cm DBH, diameter at breast height) adapted to peat, in which the carbon density is the highest in the entire Amazon: 1,391 ± 710 t/ ha.

Aquatic flora and fauna and fishing

Ichthyological studies of the Amazon Region (section from the pongos to the Manseriche pongo) indicate the presence of 156 species of fish distributed in 88 genera and 22 families, with 50 species for the Marañón sub-basin and 70 for the Santiago River. More than 30 species of human consumption have been found in lotic environments (fluvial waters) among them the gamitana (Colossoma macropomum), the paco (Piaractus brachipomus) and the yahuarachi or Llambina (Potamorhina altamazonica). In lentic environments (stagnant waters), with sewage, Satanoperca sp.., Aequidens sp.., Cichlasoma sp. (bujurquis) have been found. and many others.

The vast majority of species are not for human consumption but play an important role in the trophic chain and many are involved in the dispersal of tree seeds in riparian and floodplain areas. They may be able to remain isolated in interior lagoons and even maintain a dormant life, buried in the form of resistant eggs, like the fish of the Rivulidae family. Fish marketed as ornamentals live in streams and lagoons.

The gamitana, the paco, the boquichico (Prochilodus nigricans) and the tarpon (Brycon sp.) are migratory species that spend part of their lives in flood-prone areas. The large seasonal migrations of fish are called mijanos.

The EIA of the Chadín 2 hydroelectric project (at 800 m a.s.l.) identified some species in three aquatic communities: the periphyton, the benthos, and the fish. In the periphyton, 133 species of microalgae were found, the richest biological community. Two phyla were recorded in the benthos: arthropods and annelids, with 40 different species: mayflies, stoneflies and caddisflies, which are indicators of good quality water. The EIA also found 21 species of fish that corresponded to three orders. 7 families and 15 genera, including a new species: Cordylancystrus sp.of the family Loricariidae (carachamas).

Fishermen in the area have reported the presence of large migratory catfish of the family Pimelodidae, to which the dungaro belongs (Zungaro zungaro), which would climb the river to reproduce, and other species for human consumption such as the boquichico and the tarpon. In the Utcubamba river these last two species rise up to 1900 m s. no. m.. Both the migration patterns and spawning grounds of these species are unknown. They also fish for life (Trichomycterus sp.) and shagame (Hyposterus sp.).

Marañón fishing statistics do not seem very reliable, but the following figures have been reported by the Loreto Production Directorate:

For the year 2019, the Ministry of Production reported the unloading of 510 tons in Nauta.

In a section of approximately 150 km, between Santa María de Nieva and Saramiriza, it is consumed on average from 80 grams per person per day in the rainy season to 500 g/d in the dry season. 214 fishing zones have been identified in the section of the Marañón between the Manseriche pongo and its confluence with the Ucayali. The boquichico corresponds to 45% of consumption_.

Deforestation and overfishing (blocking streams with multiple nets) have a negative impact on fish populations. Fishing with toxic substances is also common, such as barbasco (roots of Lonchocarpus urucu) and huaca-huaca (leaves of Clibadium asperum) and also with pesticides (aldrin)., with an impact on the health of consumers.

Population along the Marañón river

In 2020, according to the National Institute of Statistics and Informatics of Peru (INEI), the population of the districts bordering the Marañón River is 668,568 people and its distribution is shown in the following table. The heights are those of the banks of the Marañón.

In the Andean parts of the river, that is, up to the Pongo de Rentema, where the river is not navigable, the population lives far from the river, often hundreds of meters above the level of the current. From Bellavista /Jaén) the river is navigable by small boats and the area of the pongos begins. Only from Imacita is the river navigable by larger boats. In the Amazonian plain, from Sarameriza the river is navigable by boats with a draft of 1.80 m and from the confluence with the Huallaga, which gives access to Yurimaguas, there is quite intense daily river traffic. Therefore, in this area, up to Nauta, many new towns have appeared with a growing population of settlers from regions such as Cajamarca, San Martín and Piura.

The population in the Andean highlands is decreasing due to emigration to the Coast and Lima, and in the Amazonian plain it is increasing with migrants from the Sierra and the Coast. For example, the population of Santa María de Nieva doubled between 1993 and 2020.

Indigenous peoples and languages

In the upper part of the Marañón, in the Áncash and Huánuco regions, in addition to Spanish, Quechua is spoken in the Quechua dialectal variety of Conchucos (Marañón and Huamalíes provinces in Huánuco, and in Ancash in the Antonio Raimondi, Fitzcarrald, Luzuriaga, Pomabamba and Sihuas provinces). The dialect variety Alto Pativilca-Alto Marañón-Alto Huallaga is spoken in Bolognesi (Áncash) and in Dos de Mayo (Huánuco).

Further north, the only place in the La Libertad region where Quechua is spoken is the town of Macania (150 families) in the district of Urpay, province of Pataz. In the Amazonas region, in the provinces of Luya and Chachapoyas, there are remnants of Chachapoyan Quechua, in clear decline.

When the Marañón reaches the area of El Muyo, it enters the region where the awajún ethnic group predominates.

The Awajún (also called Aguarunas) belong to the Jíbaro linguistic family to which the Achuar and Wampis also belong in Peruvian territory. Its population is estimated at 45,000 people spread over an area of 30,000 km² along the Marañón River and its tributaries Chiriaco, Cenepa, Nieva and Santiago, in the Amazonas and Cajamarca regions. They have also migrated to Loreto (Medio Marañón and Yanapaga River) and San Martín (Alto Mayo).

Their territories are titled, that is, legally protected by Peruvian law. In practice, in the face of the aggressiveness of oil and mining companies and Andean settlers, and the indifference of the Peruvian State, this protection may be theoretical. Originally, Awajún settlements were similar to those of the Jíbaro culture, that is, large isolated houses of extended families, living around a "strong man" or traditional chief. Beginning in 1968, the evangelical missionaries of the Summer Institute of Linguistics began to group them around their schools and churches. The Catholic missionaries did the same and now, that there are no more missionaries, these new native populations have a certain organization: community house, house of the Apu, bazaar, meeting center, etc. The Awajún were dispossessed of a part of their territory, along the Marañón, due to the colonization advocated by the government of Fernando Belaúnde Terry (1963-1968). The government of General Juan Velasco Alvarado (1968-1975) recognized them, like other indigenous peoples, the right to own their lands.

At the confluence with the Santiago River there are Wampis (or Huambisas) communities whose territory extends north to the border with Ecuador. In November 2015, representatives of 85 communities declared the Wampis a single nation (the Wampis Nation) and signed a constitutional statute defining their governing bodies and the limits of their 1.3 million-hectare territory. They have been the first Peruvian indigenous people in celebrating this act of sovereignty, shared with the Peruvian state. San Lorenzo, capital of the

Farther downstream, along the Cahuapanas River, which flows into the Marañón, there are Shawi (or Chayahuita) communities of the Cahuapana language family. The Shawi have had contact with the Spaniards since 1647 and as a result have long suffered abuses, epidemics and raids. Already at the time of the republic in his region, agro-extractive farms were established with Creole bosses who used them as semi-captive labor with the "enganche" (permanent debt to the employer).

At the mouth of the Pastaza River there are Kichwa del Pastaza communities, their language, called Inga, belongs to the great Quechua family of languages. They originally come from many ethnic groups displaced and brought together by the Jesuit missionaries who used Quechua to evangelize them in the 17th and 18th centuries. During the rubber era they were enslaved to collect rubber and groups were transported as labor to the Tigre and Ucayali river basins.

From the confluence with the Huallaga river and all along the Marañón, up to Nauta, including the Pacaya Samiria Nature Reserve, there are kukama kukamiria or (cocama cocamilla) communities of the Tupi-Guarani language family. The Kukama language has many similarities with the Omagua language, in the XVII century, spoken from the confluence of the Napo and the Amazon to the confluence of the Amazon with the Yurúa. The Quechua language was widely promoted by the Jesuits to evangelize and as a general language of inter-ethnic communication in the reductions, where indigenous people from many different ethnic groups had gathered.

In the confluence section of the Huallaga to Santa Rita de Castilla there are also Urarina communities whose language belongs to the Shimaco linguistic family. In the 2017 Peruvian census, the population that self-identified as kukama kukamiria was 10,762 people and 2,697 as urarina.

The Kukama were evangelized early by the Jesuits, who created the province of Maynas (present-day Loreto) and founded the multi-ethnic missionary center of Santiago de la Laguna (today Lagunas) on the Huallaga River in 1662, for that reason already in the 18th century had been considered as "semi-civilized" or "Old Christians". The Kukama tried to resist the Jesuits and were also decimated by various epidemics. In the rubber era they were also displaced as slaves to the Shiringales and upon their return, when rubber exploitation collapsed due to competition from English and Dutch plantations in Asia, they were exploited as laborers on agro-extractive farms that had occupied their lands. lands and belonged to criollos. Now they live distributed in small towns along the middle and lower Marañón and many are dedicated to fishing. Since ancient times they have lived in floodplains and are very well adapted to fluvial ecosystems. Their mythology is structured around the aquatic world in the depths of the Marañón River and its animals.

The headquarters of CORPI (Regional Coordinator of the Indigenous Peoples of Datem del Marañón and Alto Amazonas) is in San Lorenzo.

The failed Amazon Waterway project

In 2017 the Peruvian government granted a concession to the company Cohidro, whose majority owner is the Chinese company Sinohydro, to develop a waterway on the Marañón, Huallaga, Ucayali and Amazonas rivers, in order to facilitate fluvial transport in the dry season. It was planned to dredge a series of bad steps (23 according to the Final Engineering Study, EDI) and the entrance channel to the port of Iquitos, and install a network of limnimetric stations to know the depth of the river in real time. The improvement of the existing ports, quite primitive, nor the construction of new ones was considered.

Waterway project in the Peruvian Amazon and main indigenous peoples who have participated in the prior consultation

The referential investment was evaluated at $95m with the dredging of only 13 missteps. The volumes to be dredged to a depth of 2.40 m in those 13 mispasses would have been those in the following table. Obviously, if you have to dredge 23 bad steps, making a simple extrapolation, since we do not have the EDI figures, you would have to multiply the totals by 1.77.

The concessionaire's investment and profit must be financed by the tolls from the boats, which currently pay nothing. Within the framework of a public-private association, the State undertakes to complete the income to be obtained from tolls until the cost of the contract is covered. Until 2021, a definitive engineering study, a prior consultation with 14 indigenous peoples along the waterway and an environmental impact study have been carried out. The latter has not been completed because it had more than 200 observations. In addition, the modeling that he did of the impacts of the dredging on the rivers has been incorrect because it did not consider the period of low water. fishing areas and bad steps. But, since a correct feasibility study had not been previously carried out and the agreement of the shipping companies to pay the tolls had not been obtained, the financial future of the project, which was already more than two years behind schedule, seemed controversial. In October 2022, the Peruvian government declared that it was going to declare the project expired.

History

From the end of the last ice age to the fall of the Inca Empire

Alto Cashew

Humans have moved in the upper Marañón basin for at least 12,600 years, when the glaciers began to recede.

The engineer Augusto Cardich investigated caves next to the Lauricocha lagoon and divided his excavations into three strata according to their age. Stratum I, a pre-agricultural site (10,000 to 8,000 BC), was dated in 1959 to 9,525±250 years old. Lithic tools with leaf-shaped tips and bifacial knives were found there. The inhabitants were hunters of tarucas (Hippocamelus antisensis). In stratum II (8000 to 5000 BC) abundant flint tools were found, some very well worked. Human skeletons of 4 adults and 7 children were also found, with stone and bone tools, and camelid remains. The children were buried with elaborate ornaments as offerings. In stratum III (5000 to 4000 BC) bone tools were found, small and medium leafy tips.

In the area of Lauricocha there are many cave paintings dating from the time of the hunter-gatherers. One of the most famous is the one in the Chaclarragra cave that represents a deer hunt painted in dark red. In the heights that dominate the Marañón, on the Huánuco side, in the provinces of Yarowilca, Dos de Mayo and Huamalíes, there are many rock paintings and petroglyphs that have been surveyed but not studied or dated. and petroglyphs further north, in the Amazonas region, in the provinces of Luya and Utcubamba. There, the most famous of the shelters that house paintings is that of Chiñuña, very close to the town of Yamón and the Marañón river. It has paintings representing dancers and the hunting of auquénidos, which would be 3,290 years old, although, as in Lauricocha, more scientific studies still need to be done.

In the city of Jaén, on the hill of Montegrande, the archaeologist Quirino Olivera has excavated an enormous spiral of stone and adobe, similar to another found in Palanda (Ecuador) at the headwaters of the Chinchipe river, a tributary of the Marañón. Surrounding the spiral there is a coiled serpent and, as head, it has a gigantic character.

In Palanda, in the eye of the spiral, a tomb was found in which there was a ceremonial vessel with remains of a drink containing cocoa. Cocoa, of the "fino aroma" variety, has been dated between the years 2265 and 1885 BC. C. Both monuments belong to the Mayo-Chinchipe-Marañón culture (5500-1700 B.C.), which traded with the Pacific coast, as attested by the Spondylus and Strombus shells. found there. In exchange, travelers brought cassava and cacao from the Amazon to the coast, where the Valdivia culture flourished. Containers found there contained remains of corn starch and cassava, sweet potato and chili pepper. This is the only monumental architecture found so far in the Amazon and is, perhaps, confirmation of the thesis of archaeologist Julio C. Tello (1942), that the origins of the Andean civilizations are in the Amazon. The gold found in the tomb of the Lord of Sipán (Lambayeque) has been traced to the laundries of the Chinchipe river. According to Tello, the iconography of Chavín de Huántar, which includes animals such as the jaguar and the caiman, and the club heads, reminiscent of the hunting of heads practiced by the jungle tribes, would point to a relationship with the Amazon, downstream, following the valley. of the Cashew. However, in Chavín de Huántar no ceramic piece of Amazonian origin has been found.

In Huayurco, at the confluence of the Tabaconas and Chinchipe rivers, in a place of dense cloud forests, the archaeologist Pedro Rojas Ponce has found a place of production, during the Early Horizon period (900-200 BC.) of polished stone plates and bowls, smooth or decorated with grooves and serpents.

Other archaeological sites in the region that belong to the same culture are San Isidro in Jaén and Las Juntas and Casual in Bagua. In these last ones there are buildings of thatch (reeds and clay) that would have had a religious function and in which there are mural paintings. In one of them there is an alligator on a background of snakes. Bagua has been since the Initial Period of Peruvian cultures (2000-0 BC) an important crossroads, connecting the Coast and the Jungle, Pacopampa and southern Ecuador, and at that time it developed its own ceramic styles, first polychrome, decorated with incisions and later the so-called El Salado, polychrome and monochrome, and decorated after having been fired, which would reveal influences from the distant Orinoco basin.

In the Lower Utcubamba valley, archaeologists Ruth Shady and Jaime Miasta have found numerous ceramic remains from the Formative (1800 to 200 BC), Middle, and Late periods. At the confluence of the Chinchipe and Marañón rivers There is the Tomependa hill (380 m a.s.l.) where there are 5 archaeological mounds, in which buildings with walls painted white or cream have been excavated. The area has been intensively and systematically looted, and complete ceramics that are supposed to have been found there are now in Europe. The population consumed corn, cassava and sweet potatoes. He hunted deer and gathered frogs, freshwater crabs, and snails.

From the year 700 there is evidence of the occupation of that area of the Marañón-Chinchipe by jíbaro peoples (called bracamoros by the Spanish conquerors who could not subdue them). They are the ancestors of the current Awajún and Wampis.

Lower Cashew

In the lower Amazon there are two large ecosystems: the várzea (Brazilian term), that is, the riparian and floodable areas, and the restingas, or mainland, the non-floodable areas. In them, the domestication of plants did not precede the emergence of agriculture, except for the palm tree "chonta" (Bactris gasipaes). Cassava (Manihot esculenta) would have been domesticated in Alto Madeira and from there it would have traveled to Marañón.. In the várzea, the abundance of resources favored the growth of the populations, their sedentarization and their cultural development, while on the mainland, until today, the populations of hunters and gatherers have to move once the local resources are exhausted.

During the Middle Holocene, evidence points to a nomadic way of life. From the first millennium AD. C. there is evidence of the establishment of sedentary life in many places in the Amazon, although, apparently, not in the Lower Marañón. It has been difficult to do archaeological research in the lower Amazon because of the lack of rocks, the rapid natural decomposition of wooden buildings and artifacts, and tropical diseases. In general, in the lower Peruvian Amazon, there are rare testimonies of ancient populations. There is only the pottery found in Nazarateki, in the Ucayali, and in the Chambira and Napo rivers. There are also imprints of poles, stone artifacts, and mounds and bases of buildings. In the Chambira culture, north of Marañón, in 2000 B.C. C., bottles with a bridge handle and a double spout and figurines with a deformed head of the tabular, erect and bilobed type appear that reappeared much later in the Formative period of the Central Andes. These early pottery techniques would have entered the Amazon from the Ecuadorian and Colombian Andes according to Betty Meggers. However, archaeologist Donald Lathrap assumes that its origins would rather be in the central Amazon, near the confluence of the Amazon with the Negro River.

The Amazonian mother tongue, according to Donald Lathrap, would be Arawak, which would have spread from the highly fertile and densely populated várzeas of the central Amazon, around the confluence of the Amazon with the Negro River. Later the Tupi-Guarani would arrive, efficient warriors, who would replace the original populations and who would move along the Amazon and Marañón, and who would have reached the eastern foothills of the Andes, being the origin of the current Kukama population and of others that became extinct with European colonization. These displacements of "early potters" they would have begun, from the Central Amazon, in 3000 a. C. and they would have occupied the lower part of the Marañón towards 2000 a. c.

Other places in the lower Marañón basin where pre-Hispanic ceramics have been found are Balsapuerto on the Cachiyacu River, associated with salt exploitation, approximately between the years 1000 and 1200 AD. C., and in the Morona and Pastaza rivers, in which more than 82 sites have been identified whose stylistic chronology would go from 1000 a. C. until 1500 d. C. The complex societies of the Amazonian plain that developed in those periods participated in long-distance exchange networks, including the Andean region. The Chachapoyas culture, between the Amazonian plain and the Andes, which emerged around the year 1000 AD. C., surely played an important role as a link between both ecosystems.