Historical research indicates that both of the Andersons were buried near the White House structure, although the
precise location of the graves has been lost. Until a few years ago, at least one headstone was said
to be present in the yard area northeast of the house. The main focus of the archaeological survey described
here was to locate the positions of the grave shafts using a non-intrusive survey procedure known as thermal
imaging.
Thermal imaging is a technique used commonly in surveillance and discovery in law enforcement
contexts. The process works by detecting variations in surface temperatures between objects, registering
higher relative temperatures as light images and lower temperatures as dark images.
|
Below is an example of a
thermal image taken during the project of a modern house at the White House site. Heat from the interior of the house
makes it appear to glow in the thermal image on the right, especially under the eaves (upper right), where heat is trapped.
The wall studs are faintly visible since they provide a slight block to the radiating heat.
|
An important application of
thermal imaging technology in law enforcement involves locating recently disturbed ground, such as would be associated with buried
evidence of criminal activity. Disturbed earth absorbs and retains heat more readily than undisturbed earth. A
backfilled excavation, such as a grave shaft, will produce a bright image in relation to surrounding undisturbed earth.
It was thus proposed to scan the ground around the White House for evidence of the shafts associated with the Anderson’s
graves.
The usefulness of thermal imaging technology in law enforcement discovery work is acknowledged,
but it was unclear how well the system would work in archaeological applications--that is, how well the presumably less prominent
heat signatures of archaeological features might be detected.
|
