Archaeology Magazine - Maya Caves of West-Central Belize: Remote Sensing

During the second session of the summer 2000 WBRCP, we will be utilizing state of the art remote-sensing technologies. We are developing a unique research protocol for the collection and manipulation of cave-site data that will be used in conjunction with various remote-sensing platforms (ie. LANDSAT 5 and 7, and IKONOS). Our objective is to locate cave sites and determine the usefulness of the various remote-sensing platforms for this purpose. Similar research has proved successful for locating surface sites in the Maya area, but this technology has not yet been applied for caves. Finding cave sites is particularly important to Maya archaeology because they often contain archaeological material, much of which is undisturbed and in primary context. Because of the prevalence of looting in the Maya area it is important for archaeologists to find these sites before they are disturbed. Simply re-locating known cave sites in the jungle can be a monumental task, and finding new, undisturbed caves can be nearly impossible deep in the rain forest. We believe that utilizing this technology will aid us in the search for caves in the jungles of Belize.

We will be collecting data over the next month at known cave sites, many of which are currently under investigation by the WBRCP. The remote-sensing platforms record reflectance of electromagnetic waves from the earth's surface. We intend to collect vegetation and temperature data at the entrances of caves in an attempt to assemble a cave "signature" or signatures in the multispectral and thermal bands of the satellite platforms.

We are using a Garmin GPS III to determine locations of the research sites so that we are able to accurately locate them in the satellite images. We will record thermal information around the cave sites at two-minute intervals using three HOBO H8 family temperature loggers. One will be placed just outside of the entrance to the cave, the second on the ground atop the cave passage (where possible), and the third logger will be placed 100 meters from the cave entrance as a control. With this placement of the loggers we intend to record thermal changes in the environment caused by cooler temperatures of the air and water that come from the subterranean passages.

Vegetation, especially those species which make up the high jungle canopy, is the primary factor that affects the reflectance of the electro-magnetic information in the visible range that is recorded by the satellite. At the cave sites we will do a classification of the environment, e.g. broad-leaf ridge, pine ridge, milpa. We will also note dominant canopy species, when appropriate. Finally we will take black-and-white photographs from the ground of the canopy with a fisheye lens. The 180-degree range of the fisheye lens will provide photographs that will be used to determine the percentage of canopy coverage.

This autumn we will use GUI computer programs such as Idrisi and IMAGINE to manipulate the data and satellite images, and, we hope, to identify spectral/thermal signatures for cave sites. If such signatures exist, we will search the rest of the image for similar configurations to locate heretofore undiscovered cave sites in Belize.

Prior to arriving in Belize we prepared a LANDSAT 5 image of Belize (path 19, row 48) for use in the field. This preparation consisted of obtaining 1:50,000 scale Universal Transverse Mercator maps and georegistering subscenes of the satellite image that correspond with the study area. The LANDSAT 5 image was provided by Rick Wilk and Anne Pyburn of Indiana University, and facilities were made available by Eduardo Brondizio, Emilio Moran, and the Anthropological Institute for Training, Indiana University. This image/map will be used as a field reference to facilitate the computer manipulation of the satellite images in the lab.

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