Chapter 5

Doing Fieldwork: Remote Sensing and Geographical

Information Systems

Outline• Remote Sensing: Data at a Distance• How to Find a Lost Spanish Mission • Cerén: The New World Pompeii?• The Potential and Limitations of

Noninvasive Archaeology• Geographic Information Systems• Conclusion: The Future of Remote

Sensing and GIS

Remote Sensing

• Photographic and geophysical techniques that rely on electromagnetic energy to detect and measure characteristics of an archaeological target.

The Ancient Roads of Chaco Canyon (AD

1050)

Thermal Infrared Multispectral Scanner

(TIMS)• A remote sensing technique that uses

equipment mounted in aircraft or satellite to measure infrared thermal radiation given off by the ground.

• Sensitive to differences as little as 0.1° centigrade, it can locate subsurface structures by tracking how they affect surface thermal radiation.

Aerial Photography• Can show features too indistinct or too

large to discern from ground level.– Plants growing over buried walls are

browner because they are less vigorous.

– Buried trenches or houses contain looser, organic sediment and promote plant growth; these appear greener.

Color Infrared Film (CIR)

• Detects wavelengths at and beyond the red end of the light spectrum and can detect heat.

• Can record differences in vegetation, because plant cover affects the heat reflected from the ground.

• If differences in plant cover suggest buried features as in standard aerial photography, then it can detect those buried features.

Synthetic Aperture Radar (SAR)

• Uses radar beams to locate buried features, working on the principle that hard buried surfaces reflect more energy than softer surfaces, which absorb energy.

• In 1982, radar aboard the Space Shuttle penetrated the Saharan sands, revealing the presence of ancient watercourses, along which ancient towns lie.

Landsat Multi-Spectral Scanner (MSS)

• Used in the late 1970s, MSS images were taken from Landsat satellites and used the infrared spectrum (like TIMS) to construct false-color images that track infrared radiation.

SPOT• A French-based satellite imagery

system that can simultaneously record one or more bands of the electromagnetic spectrum.

• Some of its images have a resolution of only 2.5 meters and can be produced as three-dimensional images.

• It is unaffected by cloud cover and shadows.

Proton Precession Magnetometer

• A remote sensing technique that measures the strength of magnetism between the earth’s magnetic core and a sensor controlled by the archaeologist.

• Magnetic anomalies can indicate the presence of buried walls or features.

Soil Resistivity Survey• A remote sensing technique that

monitors the electrical resistance of soils in a restricted volume near the surface of an archaeological site.

• Buried walls or features can be detected by changes in the amount of resistance registered by the resistivity meter.

Soil Resistivity Contour Map From Mission

Santa Catalina

Ground-penetrating Radar

• A remote sensing technique in which radar pulses directed into the ground reflect back to the surface when they strike features or interfaces within the ground, showing the presence and depth of possible buried features.

Geographic Information Systems (GIS)

• Computer programs that store, retrieve, analyze, and display cartographic data.

• Every GIS consists of three components:– a computer graphics program used to

draw a map– external databases that are linked to

objects on the map– analytical tools that graphically

interpret or statistically analyze stored data

Archaeological Ethics and Remote Sensing

• In 1987, a Pawnee tribal member donated a family-owned medicine bundle to the Kansas State Historical Society with the request that it be cared for, studied, and exhibited.

• The use of noninvasive remote sensing technology fostered cooperation and goodwill, balancing the interests of Native American and scientific communities.

The Predictive Capacity of GIS: The Aberdeen Proving

Ground• The Aberdeen Proving Ground consists

of 39,000 acres of land on the north end of Chesapeake Bay.

• Much of the area is marsh and the sites are ephemeral shell middens and scatters of ceramics and stone flakes.

• Unexploded ordnance still litters the proving grounds.

The Predictive Capacity of GIS: The Aberdeen Proving

Ground• Archaeologists Wescott and Kuiper

developed a predictive model for the Aberdeen Proving Ground– They used characteristics of 572 sites

along the shores of Chesapeake Bay.– They recorded variables that

described the site locations. – They analyzed the data to discover

the best predictors of site locations.

Landscape Archaeology• The study of ancient human

modification of the environment.• From the perspective of the

processual paradigm, landscapes are places with different economic potential.

• Postprocessualism adds the social and symbolic meanings of land.

Schematic of the Keres Symbolic Landscape

GIS andthe Chacoan Roads

• Working in a region just south of Chaco Canyon, John Kantner used a GIS to test whether the roads were linked to the economic or symbolic aspects of the desert landscape.

• If the roads were for purely economic purposes, they should follow the path of least resistance between villages.

GIS andthe Chacoan Roads

• Kantner asked the GIS to find the easiest walking route between settlements connected by roads.

• Kantner found that the Chacoan roads do not follow the path of least resistance.– Perhaps they were religious paths; some

lead directly to places on the landscape that are prominent in modern Puebloan religion.

– Perhaps they helped integrate the small far-flung pueblos with the Great Houses in Chaco Canyon.

Quick Quiz

1. Which of the following is a remote sensing technique?

A. Thermal Infrared Multispectral Scanner (TIMS)

B. Aerial PhotographyC. Color Infrared Film (CIR)D. Synthetic Aperture Radar

(SAR)E. All of the above.

Answer: E• Thermal Infrared Multispectral Scanner

(TIMS), aerial photography, Color Infrared Film (CIR) and Synthetic Aperture Radar (SAR) are all remote sensing techniques. Others include the Landsat Multi-Spectral Scanner (MSS) , SPOT, Proton Precession Magnetometer and Ground-penetrating Radar.

2. ________ _________ is the study of ancient human modification of the environment.

Answer: Landscape archaeology• Landscape archaeology is the

study of ancient human modification of the environment

3. Archaeologist Kanter wasn’t surprised to learn that the GIS proved the Chacoan roads followed the easiest walking route between settlements.

A. TrueB. False

Answer: B. False• Kantner found that the Chacoan roads do not

follow the easiest walking route between settlements.

• The roads may have been religious paths, or helped integrate the small far-flung pueblos with the Great Houses in Chaco Canyon.