An Unexplored Realm in the Heartland of the Southern Gulf ... - Famsi

Campos and Marín identified structures and features on their map and assigned
them numbers 1 through 107. The numbering sequence is for identification purposes only
and has no association with the feature’s spatial or temporal position. This system was
used and supplemented in this report. The identification of additional structures
documented during the current project begins with number 108.
A Leica GS20 GPS data collection unit was used during the 2004 field season
and, in 2005, a Trimble Pro XR GPS unit was employed; both are mapping-grade GPS
equipment. Mapping-grade GPS provides sub-meter accuracy and allows the collection
of data not only as points but also as lines and polygons (Trimble 2005). Data collected
by these systems can be integrated into Geographic Information Systems that permit
correlation of aerial photo imagery, and geo-referencing of site locations (Magellan
2005).
In 2004, GPS coordinates were acquired at all survey locations. The edge of the
river cut bank, fence lines, field boundaries, and apparent architectural features were
delineated and recorded, as were the spatial locations of the Olmec throne and the soil
survey test areas. The GPS was used throughout the magnetometer survey (Figure 4.4),
and the location data layers were merged with the magnetic data to produce a spatially
accurate map (see Magnetometer Survey section in this chapter).
During the 2005 field season, mapping grade GPS was again used to locate the
control points for the total station topographic mapping segment described in the
following section. The GPS unit used during this portion of the project was a Trimble
Pathfinder Pro XR mapping grade receiver that provides real-time, submeter accuracy for
regional and site-level surveys. The rover capability is ideal for large scale projects and
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