Can nature align? The enigma of Moxos’ Lagoons, astronomy and
landscape in south-western Amazonia
JUAN ANTONIO BELMONTE (1) AND JOSEP BARBA F. (2)
(1) Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain.
(2) Centre d'Estudis Amazònics, Barcelona, Spain
Abstract
In the present essay we present a tentative archaeoastronomical analysis of the Moxos’ Lagoons,
a controversial and huge geographical network in the landscape of the Bolivian Amazonia. In
the late 1990s, a preliminary analysis of the orientation of a comprehensive and statistically
significant number of lagoons showed that only human action could explain the peculiarities of
their geometry and especially their orientation according to a main axis aligned to an azimuth of
50º and its complementary angle. Since then, the debate on the anthropogenic origin of Moxos’
lagoons has been overtly open. The absence of distinctive geographical marks in the horizon
strongly suggested an astronomical justification for such peculiar pattern. This short report
presents a first approximation to the problem, suggesting that the lagoons could have been
deliberately orientated in agreement with certain stellar positions which may have marked
selected moments of the local climatic or economic cycle, a fact which might confirm ethnohistoric references. The implications for new ethnographical research in the region are selfevident.
1. Introduction
It has been a general belief that Amazonian people did not create complex societies. The
current low population density of the river basin and the apparent nonexistence of
archaeological vestiges of any significance seemed to confirm this fact. According to
some scholars, the poverty of Amazonian soils limited the food production and made
impossible the maintenance of urban settlements of any size. However, with the
introduction of aerial images and remote-detection systems, vestiges of complex works,
which are difficult to explain within a context of a simple hunter-gatherer society, have
been discovered. This has been especially important in the area of the flooding plains,
the “pampas”, within Beni province, in the north of Bolivia, where the practice of an
intensive agriculture has been demonstrated with the discovery in the 1950s, by
engineer Kenneth Lee, of extensive areas of cultivation drained-fields, when performing
seismic prospects in search of geologic fractures that could accumulate petroleum. As
shown in Figure 1, this is precisely the area of the lagoons and the scene of the old
culture which has given the name to the region under discussion, Llanos de Moxos
(Denevan, 1966; Iskaenderian, 2009).
During several years of fieldwork, Lee compiled an enormous amount of information
and developed an elaborated theory arguing that the rest of undoubted and hypothetical
human works, and other archaeological remains, that could be found along Moxos
actually integrated a cluster of structures elaborated with the aim of colonising the huge
inundating region of the pampas (see Figure 2). In the 1990s, the second author met Lee
in Santa Cruz and started work together, analysing the different elements of the cluster
−lagoons, channels, embankments or “terraplenes”, dams, hillocks or “lomas”, etc.− and
studying their abundance and spatial distribution. Another objective was the
environmental study of Llanos de Moxos throughout history, and the rescue of
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sustainable productive technologies of possible present application. In 1994 the Centre
d' Estudis Amazònics (CEAM) was created in Barcelona with the purpose of supporting
all these works (Barba, 2003; Barba and Miró, 2003), including the creation of the
“Estación Piscícola Mausa”.
Figure 1. Map of the Amazonian region showing the area occupied by the Llanos de
Moxos and the region of the Mamore River basin where most of the lagoons are
located.
The most important case study was indeed the one of the lagoons (see Figure 3), which
geometry strongly suggested a possible anthropogenic origin despite the works of
George Plafker (1964) and other geologists who considered the lagoons as a work of
nature. In 1995, an agreement between CEAM and the Institut Cartogràfic de
Catalunya (ICC) allowed, for the first time, a complete cartographic study of the area
though satellite images (see Figure 4), an inventory of the lagoons and a structural and
design analysis. First results were presented in the late 1990s (see e.g. Figure 5), the
main conclusion being that only human action could explain the peculiarities of their
geometry and especially their orientation according to a main axis aligned to an azimuth
of 50º and its complementary angle (Barba et al. 1998; Barba and Viñas, 2000). The
absence of distinctive geographical marks in the horizon suggested a possible astronomical
justification for such peculiar pattern. Since then, the debate has been overtly open.
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Figure 2. Ancient human landscape in Moxos in the dry (left) and flooding (right)
seasons, respectively. Upper images show a couple of hillocks and lower images a
complete network of drained-fields. Notice how the hillock and fields remain above the
level of the water during the flooding season. Images by courtesy of CEAM.
Figure 3. Different aerial images of Moxos’ lagoons. (a) The aligned Montevideo twin
lagoons, strongly suggesting human origin. (b) A lagoon keeping its form and size
during the flooding season. (c) An area showing four nearby lagoons with different
states of preservation −the ones at the left and right are the result of lagoon fusion−. (d)
A fish-station (“estación piscícola”) close to Laguna Mausa where new fish-raising
techniques with autochthonous species have recently been implemented demonstrating
the capability of the lagoons for this sort of economic activities. Images by courtesy of
CEAM.
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Figure 4. Satellite image (up) of an area rich in lagoons in the left bank of the Mamore
River. The lower image shows a schematic plan of the area where still extant and dry
lagoons are marked by different tones of colour. Grey arrows indicate the two dominant
axes of the lagoons. Images by courtesy of ICC and CEAM.
Figure 5. The original histogram of orientations showing the non-random orientation of
the lagoons which is at the basis of the present investigation (From Barba and Viñas,
2000).
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2. Discussion
According to the hypotheses discussed above, Moxos’ Lagoons would certainly be the
largest archaeological remain of the Amazonia, even of pre-Columbian America. The
region studied covered a surface of more than 80,000 km2 (1170 km2 occupied by the
lagoons only), and would have represented a huge colonisation effort of a flooding plain
comparable to the one of the Egyptian civilization in the lower valley of the Nile, place
where astronomy played a most relevant role in the process (Belmonte, 2009). Little is
what we know about the society that presumably created the lagoons −thought to be
used as huge fish-raising factories− and all related structures, neither of the time and the
cause of the collapse of the system which has already been produced long time ago at
the moment of the arrival of Spanish Jesuits in the 17th century. However, an early
dating c. 800 B.C. could be suggested from ceramics found in prospect excavations of
certain “lomas” (Doughgerty and Calanda, 1984). Amazonia may indeed have a long,
ignored and fascinating history.
The present work includes a new archaeoastronomical insight into the data of the
lagoons. Some 370 lagoon axes, and their perpendiculars, have been analysed in an
attempt to shed some light to the problem through a multidisciplinary approach. The
declination histograms (see Figure 6) show that the orientation of the main axes −either
major or minor− of the lagoons can not be explained by solar or lunar orientations.
However, the diagrams demonstrate that the lagoons could have been deliberately
orientated in agreement with certain stellar positions which may have marked selected
moments of the local climatic cycle, considering that the rainy season, after several
months of severe drought, starts during the month of October. This is a fact which might
confirm ethno-historic references of the late 18th century (see e.g., Eder, 1985; Barba,
2009). Two alternatives can be analyzed.
On the one hand, if the major axes of the lagoons are considered, the main peaks of the
histogram could be related to the rising of Arcturus (see Figure 7). This star had its
heliacal rising at the end of October during the first quarter of the first millennium B.C.
At the present moment, we lack information relating this star to any aspect of the
culture across Llanos de Moxos. However, the Kobeua tribe of Brasilian Amazonia
identifies the area of Böotes as a celestial piranha with Arcturus at its tail (Staal, 1988).
We may speculate with the idea that lagoons’ builders may have seen in the same area
of the sky a sort of fish-constellation −perhaps a “pacu” instead of a piranha−
presumably related to the fishing practices supposedly practised at the lagoons. The
heliacal rising of this constellation could have been seen as a propitiatory phenomenon
related to the economic cycle of the region. However, on the other hand, if the minor
axes are considered (actually, the main axis of the dam enclosing the lagoon), then the
histogram shows that the highest peaks could be easily explained by orientations to the
bright stars of Centaurus and Crux. These last stars and asterisms, especially Alpha and
Beta Centauri, may have had an important symbolic aspect in the Cosmovision of the
ancient Moxeño culture since they were amply recognized by other neighbouring −but
not necessarily contemporary− cultures such as the Inca of the highlands (Bauer and
Dearborn, 1998) or, specially, the Tupi-Guarani of the upper Chaco (Pereira Quiroga,
2004) who see in that region the image of a giant ñandu or “piyu”, the American ostrich
(see Figure 8). Alpha and Beta Centauri also had their helical rising −and setting by the
way− at the end of September in the first millennium B.C. and could have acted as the
heralds of the incoming rains and flooding.
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Figure 6. Declination histogram of the orienting data of 370 lagoons in Llanos de
Moxos: (a) orientation of the major axis, (b) minor (or dam) axis. There are no
significant peaks in the luni-solar range (dot- and dash-vertical lines, respectively),
strongly suggesting a stellar explanation for the most significant peaks, providing the
anthropogenic origin of the lagoons. The stars of Crux plus Arcturus, Rigil Kent and
Hadar have been considered as the only reasonable candidates. See the text for further
discussions.
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Figure 7. The heliacal rising of Arcturus c. October 28 1000 B.C. following the
dominant azimuth of the main axes of Moxos’ lagoons. Arcturus might have belonged
to a fish-like constellation heliacally rising at the arrival of the rainy-flooding season.
Figure 8. A photograph of a “piyu” (a) and its corresponding local rock-art (b) and
celestial (c) counterparts. The head and neck of this huge constellation might also have
been the reference for the orientation of the lagoons, providing its importance could be
proved for the ancient “Moxeño” culture. Images by courtesy of CEAM (a,b) and
Gonzalo Pereira (c).
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At the present state of knowledge, we are unable to clearly fix a preference for any of
the two alignments discussed: Arcturus with Böotes or the bright stars of Centaurus plus
Crux. Both offer an interesting and appealing possibility for the astronomical
orientation of the very likely anthropogenic origin lagoons. Indeed, the implications for
new and extensive ethno-astronomical research in the region, in an attempt to further
investigating local sky-lore and its possible relationships with the lagoons, are selfevident.
Acknowledgements. This work is partially financed under the framework of the
projects P310793 “Arqueoastronomía” of the IAC, and AYA2007-60213 “Orientatio ad
Sidera II” of the Spanish MICINN.
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