Some minerals characteristic of the soil of the protected site are also contained in the soil of the private site. The basket was too encrusted with soil to be examined accurately. The basket was excavated on private property. No minerals characteristic of the soil of the private site were detected on the basket.
A certain type of prehistoric basket has been found in only two locations, one on private property and the other on a protected archaeological site. An electron microscope was used to examine one such basket. Unless an artifact has been thoroughly cleaned, an electron microscope will detect on the artifact minerals characteristic of the soil of the site where the artifact was excavated. Yet no minerals characteristic of the soil of the protected site were detected on the basket, although the basket was still encrusted with soil from the site from which it had been excavated.
The information in the passage, if correct, most strongly supports which one of the following?