See? I was right. ;^)
Yes, those archaeologists are half-witted and they recently allowed destruction of the site that is their job to protect. This August, they used backhoes to dig into Monks Mound, the largest central mound on the Cahokia Mounds World Heritage Site. They removed over 30,000 cubic feet of the mound with backhoes, and dumped it into dumptrucks without any screening or archaeology done. They also dug into a large cremation chamber that was surrounded by limestone slabs. It is frustrating that they could do this since the laws prohibit it. They claimed to be doing this to “save the mound” from rainwater eroding it all away. Now they are denying everything about the fiasco.
Oh and you are also right about the tablet representing a carbon credit. Do you know where you read that good information?