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Geoglyphs of Acre

Date of Submission: 30/01/2015
Criteria: (iii)(iv)(v)
Category: Cultural
Submitted by:
Permanent Delegation of Brazil to UNESCO
State, Province or Region:
Ref.: 5999

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The Acre Geoglyphs are earthen excavated structures in the ground and formed by low walls and ditches representing geometrical figures of different shapes. These enclosures were found in the southwestern region of the western Amazon, most predominantly in the eastern portion of the state of Acre, located in areas between streams, creek springs and wetlands, associated mostly with the Acre and Iquiri rivers.

Currently in the state of Acre, 306 geoglyphs type archaeological sites have been identified that are made up of 410 earthen structures. However, with the development of archaeological research in the state, the growing number of localized sites is steeply increasing.

The first records of these sites date back to the 1970s when researcher Ondemar Days, under the National Archaeological Research of the Amazon Basin Program (PRONAPABA), located eight earthen structures in Acre. However, it was not until the 2000s that these archaeological sites had mediatic projection and were subjected to systematic scientific interventions.

Archaeological research in these areas, although sparse if we consider that the number of geoglyphs increases constantly, gives awareness of important information about the management of the Amazon landscape by indigenous groups that inhabited the region between approximately 200 BC - 1300 AD, and suggest a new paradigm over the Amazon occupancy model for dense pre-colonial societies.

It is considered that the peculiarity of landscape transformation, forms, techniques and dimensions of geoglyphs represent beneficial in the disclosure of a unique archaeological heritage from the point of view of the pre-colonial occupation in the Amazon.

Although there is no single interpretation between archaeologists and other researchers investigating the issue on the function and use of geoglyphs, general conjectures seem to converge on the idea that these are collective social spaces for ceremonial, symbolic, ritualistic use, or even for residences.

The study of these earthen structures increasingly confirms that the process of occupation and settlement of the Amazon region, in the first millennium A.D., was undertaken by numerous indigenous groups and with a great technological capacity to modify the land and floodplain environment, imprinting their identity on the landscape features.

By its exceptionalism and relevance to the understanding of human agency in the pre-colonial period, such sites represent a unique example of the historical and social heritage that leads to new perspectives for their preservation, management and dissemination of these cultural goods. They also hold great importance for the Amazonian identity by constituting a resultant cultural landscape of social and symbolic marks that express not only the technological capacity to manage the environment, but above all, the landscape of indigeneity.    

Justification of Outstanding Universal Value

Criterion (iii): In the context of pre-colonial indigenous Amazonian occupations, scientific research has identified hundreds of archaeological sites formed from soil transformations and the constructions of anthropogenic landscapes, produced especially in the first millennium A.D. In this period, there was a population density throughout the region and optimal use of land and the environment floodplain, whose marks are noticeable on the landscape to the present day.

In that period, it has been noted a greater cultural tradition of creating cultural landscapes by modifying the environment to the greater use of the rainforest. However, considering the ingenuity undertaken by pre-colonial indigenous groups for the excavation of large earthen structures, geoglyphs are remarkable as it shows the human agency to model the landscape in the form of complex and precise geometric designs, often composed of two or more structures that can be connected by straight ditches and dirt roads.

The ethnic affiliation of the builders of the geoglyphs has not been precisely pinpointed yet, though some recent research suggests a possible correlation with the Arawak and Takana occupation (Manchineri, Apurinã and others) in the areas between the Acre and Iquiri rivers, undertaken in the first centuries that followed the European conquest in this portion of northern Brazil.

The large scattering of these hundreds of structures in eastern Acre indicates a significant exchange of ideas in the pre-colonial period, exceptional for the understanding of indigenous cultural contact to the wide geographic ranges in the rainforest.

Criterion (iv): The geoglyph type earth structures are the most durable, visible and significant evidence of the presence of indigenous peoples in Acre. In addition, within the range of archaeological evidence, more precisely at earthwork sites, they demonstrate the creativity and ability to handle the environment that preterit populations had to significantly modify the natural environment and create a long-term landscape.

The geoglyphs constitute real estate and are monumental earthen constructions related to an important period in the history of Brazil’s occupation of the West Amazon by a group that built hundreds of enclosures surrounded by ditches and low walls in geometric shapes, following a similar architectural technique that has spread over a wide area, with local innovations in format, size and configuration.

The aforementioned structures represent an unprecedented technological innovation by indigenous peoples in the pre-colonial period, as only in the Amazon such earthen structures were built in a tropical forest area by peoples who did not use metal tools. The structures in various geometric shapes allow the perception of the great regularity of construction techniques adopted, by which one can infer the use of measuring instruments, as much as mathematical calculations on the dimensions (ranging from 10 meters to 385 meters wide, a diameter in the case of circles and sides in the case of squares) and the depth of the figures and its trenches, which are about 11 meters wide by 1.4 meters deep. These measures do not reflect the unique situation of these ditches, which today are partially covered by carried sediments that have eroded over the years. Excavations at some sites have shown that sedimentation can reach up to two meters. Originally, therefore, trenches were two or more meters deep.

Regarding its morphology, research conducted to date indicates that there is great variability of the geometric shapes of earthen structures, where there are designs in the shape of one or two concentric circles, squares and rectangles, where sometimes there are interconnections by land paths and straight ditches. They can occur in an isolated way (only one ground structure) or be associated with each other, where a set of structures formed by up to six geometrical designs can be observed.

In addition, as it doesn't happen in the same way elsewhere in the world, they are of exceptional value because they bear witness to the ingenuity, aesthetic and mathematical principles that resulted in geometric designs with exact dimensions.

Criterion (v): Although there are enclosures surrounded by ditches in other parts of the world, the location, configuration, the preoccupation with the geometry of the forms, and the historical significance of Acre Geoglyphs in the Amazon are unique.

These sites have been built from the development of engineering techniques related to geometry and drainage systems, being located in areas between streams and wetland springs, associated mostly with the Acre and Iquiri rivers.

Despite the standardization of techniques, different configurations observed in the sites with more than two structures qualify as unique examples. As these are constructions that had earth as raw materials, and appropriated landscape elements such as edges and plateaus’ elevations, as well as the sources of rivers to make their morphology, they constitute a landscapes altered by human industry that remain to date marked on the ground.

The groups that have built the geoglyphs in Acre opted, preferably, for the highest location and often on edges of plateaus that crown the valleys, in full view of the surroundings. In some cases, the trench has been excavated by the plateau edge. Its location in the landscape also indicates concerns with defense, suggested by the positioning of these gigantic structures in the highest possible places.

To the extent that the structures mentioned have been built by a physical transformation of once natural landscapes, taking into account the durability of these constructions that resisted at least a thousand years, it is clear evidence of the considerable human agency on the environment. The exceptional value of these sites contributes to the understanding of the Amazonian regional and local history, being witness to the cultural diversity of the landscape and the indigenous peoples’ history in America.

Statements of authenticity and/or integrity


For the archaeological site to be considered a testimony or representation of a historic epoch or people, it is also necessary to contain archaeological remains in sufficient quantity and quality so that it has the potential to communicate and provide interpretation of the historical period, the place, the actions, the science knowledge, and the ways of life of the people that are represented.

In the state of Acre, the potential of the archaeological heritage is extremely valuable, and the geoglyphs represent peculiar landscape transformations, with important differences as to their morphology, size, timing, location and control construction techniques in the rainforest.

The construction techniques and the morphology of the structures were not replicated in other parts of the Amazon, which gives them a unique  feature with regard to the transformation of the cultural landscape. Although there are enclosures surrounded by ditches in other parts of the world, the location, configuration, and attention to the geometry of historical forms and meaning of these sites are unique. Moreover, only in the Amazon such structures were built by people that, as for the modern knowledge presents, did not know or did not dominate metallurgy. Because it does not occur in the same way elsewhere in the world, they are considered of exceptional value, as they bear witness to the ingenuity, aesthetic and mathematical principles, as much as the capacity to diffuse ideas of peoples that left no written accounts of their history.


The archaeological sites are protected at the federal level by the Archaeological Law (Law No. 3924 of July 26, 1961), which protects these cultural commodities as to their economic exploitation, destruction or mutilation. The Geoglyphs of Acre, although under the protection of this legal instrument, are located in the main production areas of the state of Acre and exposed to various levels of threats such as deforestation, opening of highways and roads, extensive cattle, among others. Nevertheless, its elements and dimensions express the values that characterize its monumentality, so that it remains, to this day, with the morphological and unique location patterns. 

Even those sites that have been impacted by recent human activities preserve archaeological remain subject that are able to contribute to the understanding of the cultural characteristics of its builders and its architectural and engineering skills.

It can also allow the systematic collection of relevant data for archaeological research and the consequent construction of scientific knowledge about the historic and cultural processes of indigenous groups that occupied the Amazon region in the pre-colonial period.

In the case of geoglyphs, visibility is critical to communicate or convey its meaning, and land structures identified with its varied formats present the combination of elements that give them shape, space, location, technical style and constructive.

Comparison with other similar properties

The peculiarity of the transformation of landscapes, forms, techniques, ingenuity and dimensions of geoglyphs are exceptional vestiges of indigenous occupation in the Amazon region. Sites surrounded by ditches and low walls of earth, as well as rocks, still occur in Peru, Bolivia, the United States, the British Isles, Portugal and France, but possess very particular patterns.

In Latin America, for instance, reference can be made to the Nazca Lines located in Peru and declared a World Heritage Site in 1994. They are located in an arid environment of the Peruvian coastal plain and are dispersed over an area of 450 km². It is lined with rocks and soil built in the period from 500 BC - AD 500 and, unlike the Acre land structures, represent figurative motifs, and stylized plant, fantastic beings and zoomorphic representations. Its functionality is related to rituals associated with astronomy, and with respect to construction technique combines excavations in the land associated with rock alignments.

In neighboring Bolivia, earth structures occur in high relief in Llanos de Mojos in the department of Beni. The structures are high fields for cultivation and irrigation canals associated with Arawak groups arising from the lowlands of South American far north. They were built between 400 BC - AD 1300, in relation to contemporary geoglyphs of Acre.

In North America, there are also archaeological sites composed of earth structures, i.e., the Monumental Earthworks Poverty Point in the United States, formed by five stacks six concentric semi-elliptical ridges separated by shallow depressions and a central square. With regard to its functionality, it appears to have been built for residential and ceremonial purposes by fishermen-hunter-gatherer groups between 3700 - 3100 BP. The site is located in the present state of Louisiana on the east bank of a high geographical feature on the summit Macon (Mississippi Valley), which is approximately 2m to 3m higher than the adjacent plains and prone to flooding. Its exceptionalism lies in the facts that it has been built by groups of hunter-fishermen-gatherers, as well as the monumental scale and integrity of the site.

Comparing the construction chronology of similar earth structures, a diverse phenomenon of transformation can be seen of the landscape undertaken by Amazonian indigenous groups that testify to the ingenuity, technological knowledge of large regional dispersion.

In the state of Acre these practices have been done in a lasting and intense way. Acre Geoglyphs represent an exchange of ideas and cultural landscapes processing practices that safeguard the peculiarity of having been built in the Amazon region by pre-colonial indigenous groups without the use of metal and measuring tools. Added to this, its geometric forms and exact dimensions differentiate including the other archaeological sites identified in the Amazon and in Brazil.

The indication of Acre Geoglyphs as World Heritage is indispensable for the recognition of indigenous cultural expressions that occupied the Amazon region in the pre-colonial period and that changed the landscape with monumental ingenuity. Such archaeological sites can provide an understanding of the perfect integration between man and nature, which is fundamental to the indigenous history of forest peoples and humanity as a whole.