GPS Mapping of Rano Raraku
Interior
July-August 2004
Field Crew
Jo Anne Van Tilburg, Ph.D, EISP Director
Cristián Arévalo Pakarati, EISP Co-Director
Matthew Bates, Surveyor
Alice Hom, EISP Database Manager
Debra Isaac, Graphic Artist
Bill White, Photographer
Goals and Methods
Maps and images created by Chilean governmental agencies
over three decades were reviewed in preparation for creating the published
map of Rano Raraku in Cristino et al. Atlas Arqueólogica de Isla
de Pascua, 1989. A key base document for the latter was the plan
of the volcano created by Lt. D.R. Ritchie of the Mana Expedition
to Easter Island, 1914. Five archaeological zones were created in
Rano Raraku: interior and exterior slopes, interior and exterior
quarries, and upper exterior quarries. Two quarry zones, designated
C and D, in the interior, were outlined but not mapped.
The goal of EISP’s seasonal mapping effort from 2002-2004
in the interior of Rano Raraku was to map all statues, outline the
papa, and fully delineate the quarries in Areas C and D; to
compile a contour map of the area showing the main topographical features,
and to localize all previously mapped and numbered statues that are
standing or fallen on the interior slopes.
An existing GPS station approximately 10 km west of Rano
Raraku was established by NASA in 1998. In 2000, we placed our survey
on the GPS datum WGS 84 and the UTM (Universal Transverse Mercator)
projection zone 12. This is the same projection as was used for the
previous survey and, therefore, provides consistent data. We established
four base stations in Rano Raraku on the south side of the volcano
and marked each by steel pegs placed level with the ground. These
are located away from the main path and not ordinarily visible to
passersby. Another three points were established in Area C and marked
by wooden pegs driven in flush with the ground. These pegs were also
placed away from paths so that they would remain inconspicuous and
undisturbed.
In 2002, we surveyed to centimeter level accuracy using
two Ashtec GPS single frequency satellite receivers to gain latitude,
longitude and elevation above sea level. The attitude of the statues
was also recorded: the direction in which the statue faced; the forward
slope, and the sideways/lateral slope. In 2004, we used Trimble 5700
equipment. Our major field emphasis was the collection of additional
mapping points that would allow the further exposition of design details
on selected statues and quarries. The pace of work was approximately
300 survey points collected per day for a total of 2200 points collected
in Sections C and D.
In the Field
A few interior quarry features in the Atlas were
impossible to relocate without additional identifying information.
On the exterior slopes, eight statues or possible statues shown in
the Atlas and numbering RR-002-209, 215, 216, 226-228, and
231-232 were not relocated due to new rock falls or erosion of identifying
features. In a few instances, we found that the orientations, head/base
relationships or minor archaeological details (i.e. presence or absence
of taheta) of several statues on both the interior and exterior
were inaccurately indicated on the Atlas. These anomalies will
be rectified on our forthcoming map and all available identification
numbers assigned statues by previous investigators will be cross-referenced.
Findings
A total of 139 statues, from shaped block to partial
form to finished, fully detailed figure, were mapped in 19 discrete
interior quarries—42 more than previously suggested
Quarry descriptive details constitute an additional,
vast quantity of information, and include carving canals, transport
canals, papa surfaces and configurations and tool marks. Important
and previously unrecognized rock art on statues and in quarries was
documented. These data will be integrated into a separate but parallel
study of rock art iconography currently underway.
None of the individual quarries are directly linked,
but internally some of them show a degree of planning. Some quarries
appear to have been practice or teaching areas for such important
features as statue heads and faces. As Routledge noted, narrow carving
canals, some very steep and dangerous, are cut into the bedrock alongside
and at the top and bottom of roughed-out blocks. These average about
50 cm wide, and some are stepped. Carvers stood in these canals to
work.
Research, Conservation and Outreach
The value of the EISP database is that it supports reconstruction
of the prehistoric Rapa Nui human population as a component of ecological,
political, and esoteric systems. It combines analytical tools with
social theory to contribute a unique perspective on island change.
Its use facilitates the semiotic analysis of prehistoric Polynesian
spatial organization. It is complementary to other ecological, geographic,
economic, and social analyses in Pacific Studies, and integrates Rapa
Nui into the larger and better understood East Polynesian interaction
sphere. Finally, it provides insight into the long-term development
of human systems, allowing visualization of historical and ecological
linkages of the past with the present and future.
In 2004, our condition reporting system was reviewed
by members of the Getty Conservation Center staff. As a base-line
inventory with time depth, it was deemed a useful tool for conservators;
however, some categories of data were revised, redefined, or renamed.
These new-format statue condition reports were then completed by 2004
team members for every statue documented in the interior slopes and
quarries, and for those standing or fallen on the exterior.