One of the most enduring archaeological mysteries of ancient
Peru are the so-called Lines of Nasca or geoglyphs which consist
of giant geometric forms (triangles, trapezoids, parallel lines)
as well as biomorphs (birds, plants, and mammals) etched into
the surface of the desert of southern Peru, especially in the
drainage of the Río Grande de Nasca. The geoglyphs were
constructed by clearing the surface of small stones darkened by
desert varnish, exposing the lighter soil beneath. Some of the
geoglyphs are over a kilometer in extent and are located in all
parts of the drainage, although many are concentrated on the Pampa
de San Jose, near the modern city of Nasca. The majority of the
lines can be dated to the Nasca Culture (0 to 700 A.D.) on stylistic
grounds (the biomorphs are identical in iconography to that painted
on Nasca pottery--see Proulx 1968), and by the presence of broken
fragments of Nasca pottery scattered on the surface of the geoglyphs.
However, Clarkson (1990) has argued convincingly that some of
the linear geoglyphs date to the later Middle Horizon (600-900
A.D.) and Late Intermediate Period (900-1476 A.D.), thus suggesting
that the technology of constructing geoglyphs was cross cultural
and formed a local tradition on the south coast of Peru.
First discovered in 1927 by Mejía Xesspe (1940) who thought
they were ancient roads, the geoglyphs received only sporadic
attention until the 1940's when American geographer and historian
Paul Kosok visited the pampa and happened to observe the sun setting
over the end of one of the lines on the day of the winter solstice
(Kosok, 1965). He concluded that the geoglyphs served as an ancient
calendar and that the lines marked the position of the sun at
different times of the year or pointed to various stars or constellations.
His disciple, Maria Reiche, spent the remaining 40 years of her
life recording the geoglyphs and expanding on the astronomical
theory (Reiche 1968, 1974 inter alia). Today this theory has been
largely discounted as a result of the investigations of Gerald
Hawkins, an astronomer with the Smithsonian Astrophysical Observatory.
Using modern computers, Hawkins found only random correlations
between the position of the geoglyphs and the astronomical features
(Hawkins, 1969). Anthony Aveni (1990), an archaeoastronomer at
Colgate University, has also argued compellingly against the astronomical
Over the years many speculative explanations have been proposed
for the function of the geoglyphs. Among these are several which
are completely unscientific and deserve little attention: Von
Daniken's (1968) argument that the lines served as landing strips
for visits by ancient astronauts; Rosell Castro's idea (1977)
that they were remnants of cultivated fields; and Henri Stierlin's
suggestion (1983) that the cleared areas served as giant textile
workshops. A more credible theory, based on ethnographic analogy,
proposes that the lines were used as ritual pathways leading to
sacred locations (Morrison 1978; Silverman 1990; Aveni 1990, 1996).
This model includes arguments pointing out the similarity between
the Inca "ceque lines" (a series of invisible lines
radiating out from the center of the capital city of Cuzco connecting
shrines as well as delineating social or kin-related space) to
similar radiating Nasca Lines or "star clusters" present
on the Pampa de San José (Urton 1990; Aveni 1990).
Finally, there are theories that involve the correlation of the
geoglyphs with water in some manner. Mejia (1940) was one of the
first to imply a similarity between the linearity of the geoglyphs
and filtration galleries or puquios present in the Nasca Valley.
Rossel Castro (1977:209-216) argued that just as the aquifers
formed an irrigation network underground, the geometrical figures
delineated a pattern of ancient fields and irrigation systems
on the surface. However, modern studies using aerial photography
have not supported this hypothesis. In 1986, Aveni published a
study indicating that the orientations of the triangles and trapezoids
are statistically correlated with the flow of surface water, and
that taken as a whole, the lines are most likely associated with
"a ritual scheme involving water, irrigation and planting"
(Aveni 1986:39). Reinhard (1996:56) using ethnographic and ethnohistorical
data, has argued that a strong relationship exists in Andean tradition
for a connection between water, fertility and mountain worship.
He suggested that "some lines, especially the large triangles
and rectangles, may well have served as symbolic connectors with
water sources (rivers, mountains, the ocean) and were sacred areas
where fertility rites were carried out ."
In 1996, Johnson (1999; 1998) proposed a new explanation of the
function of the geoglyphs based on his fieldwork and observations
in the Nasca drainage. This hypothesis argues that some of the
geoglyphs mark the path of aquifers which carry water through
geological faults. This is not an unreasonable explanation given
the geologic setting. This area of Peru is located in one of the
most active seismic zones of the world. Faults are common. These
faults are an integrated and interconnected network that can collect
water in one part of the region and conduct it across the valleys
to locations where it can be reached by digging puquios or wells,
or to locations where the water table is high enough for springs
or seepage to be present on the surface. Due to insufficient surface
water in the river system, the ancient inhabitants of the drainage
settled in locations adjacent to geological faults which provided
water from the aquifers. Thus, there is a strong correlation between
archaeological sites, geological faults, aquifers, fresh water
and the geoglyphs which mark their location.
This hypothesis differs significantly from other "water-related"
explanations in that all earlier models were based on the location
and flow of surface water while Johnson's hypothesis recognizes
the importance of subsurface water flow and the role of the structural
geology and hydrology in understanding the mechanism of its transmission.
The Pre-Columbian inhabitants of the drainage, through familiarity
and a basic understanding of their environment, were able to use
geoglyphs to mark the location and flow of the aquifers.
A team of scientists and experts was assembled to test this
new hypothesis. The team consists of David Johnson, Donald Proulx,
an archaeologist specializing in Nasca culture and Stephen Mabee,
a geologist with expertise in hydrogeology. The purpose of assembling
this team was to apply standard hydrogeological, geological and
geophysical techniques in concert with archaeological methods
and gather evidence that would either support or refute the hypothesis
proposed by Johnson (1999; 1998). Proulx has conducted an archaeological
survey in the lower Nasca and Río Grande valleys while
Johnson and Mabee have examined the geology of the subterranean
hydrologic systems using a combination of geologic mapping, shallow
subsurface geophysical techniques, surveying and water quality
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