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Type of Film 
Most of the earlier archeological investigations utilized black-and-white 
panchromatic photography—probably because this was the least expensive and 
most common type of coverage available. Panchromatic exposures made with a 
minus-blue filter are still considered quite useful, and may be regarded as 
fairly "standard” for preliminary reconnaissance flights. 
A number of investigators have reported tests that were conducted to com 
pare color or color infrared exposures with black-and-white photography, but 
such comparisons have proven inconclusive due to differences in timing, scale, 
weather, or other non-controlled experimental factors. There does seem to be 
general agreement that color exposures are superior to black-and-white photo 
graphs, even when that superiority is limited to a saving of interpretation 
time. And color infrared photography is especially favored for mapping sub 
surface details, such as buried foundations, walls, and other covered features. 
It might also be surmised that color or color infrared exposures should also 
be superior for detecting soil marks and certain classes of crop or plant marks. 
Since a few studies have successfully utilized black-and-white prints made 
from color infrared negatives for interpretation, it is surprising that very few 
tests of black-and-white infrared emulsions have been conducted. Furthermore, 
diapositives made from black-and-white negatives will generally yield far more 
detail than paper prints from the same negatives—yet this interpretation aid 
has rarely been utilized. 
There is obviously a need for some carefully controlled experiments re 
lating to the evaluation of photographic scales, film-filter combinations, and 
the question of prints versus diapositives for archeological interpretation. 
Until this is done, no definitive photographic specifications can be formu 
lated nor recommended. 
Infrared Scanner Imagery 
While there are several possibly useful non-photographic remote sensors 
available to the archeologist, imagery from infrared scanners has received the 
most attention. Both radar and ultraviolet sensors have been utilized in other 
scientific disciplines, but the infrared portion of the electromagnetic spectrum 
appears to have a greater potential for archeological reconnaissance. No mat 
ter what types of non-photographic sensors are employed, the resulting imagery 
is commonly used to supplement rather than replace conventional photographic 
coverage. 
The potential of infrared imagery is based on the fact that buried or 
faintly visible features may absorb or emit thermal energy in amounts that 
differ from that of the surrounding terrain, thus providing a spectral "signa 
ture" (i.e., tonal contrast) that may reveal a favorable site location. 
As an example > interpretation of infrared imagery led to the discovery of 
prehistoric agricultural plots in northern Arizona—a faintly linear feature 
that was barely visible on panchromatic aerial photographs. The thermal char 
acteristics of these plots, located in an area of volcanic ash deposits, pro 
vided differential heat emissions that produced a definitive pattern on the 
scanner imagery.