There is a really interesting discussion of the August 2007 excavation of Monk's Mound at Cahokia going on on the Talk Page for the Wikipedia entry for Cahokia. I was there was a tourist when excavation began and took a lot of photos, including some of the excavation. Someone has posted the following report of the situation.
Cahokia Mounds management did not have a permit to dig into monks mound. The Illinois Historic Preservation agency gave them permission to remove only the historic fill. The site director did this on his own initiative. I saw the letters on the IAS website detailing the site management's explanation of the work on monks mound. They claimed to be doing this work to reduce the risk of erosion and to correct the slumpage issue which occurred over 20 years ago. Their comments to the Illinois Archeology Society are an indictment that they never even considered the archeology when the 30,000 cubic feet of monks mound was torn out of the mound from three separate areas. The site management explanation makes the problem apparent that they did not consider the archaeological impact that this work would have. The fact is that the mound is actually a series of ancient sacred temples stacked on top of one another that the mound may have been covered with elaborate earthen layer of colored in blue, red, white, black, grey, brown, and orange soils. The site management never mentioned the other "Rejected Possibilities" that were proposed for this work in Cahokia Archaeological Society meetings. The website also makes it clear the professional archaeological community had no idea that this work was going to be done. I served as Vice President of the Cahokia Archaeological Society for 2004-2006 and this work of digging deeply into the mound was never mentioned to the CAS. However, the site management did state in the CAS meetings they said they were looking forward to doing some "minor cosmetic work" on the mound. An elaborate earth painting or series of earth paintings covering the mound is a real possibility considering the complexity of color use in the top 10 feet of the surface of the mound. The unfortunate fact is that no floats were taken, no artifact bags lying around, or clip-boards were on site, No screening took place and the dirt was removed with track-hoe (no hand excavations going on at the time of destruction), and the dirt was piled up in multiple areas around the mound. As of August 25th, the large piles of dirt were still piled on top of monks mound but the excavations were completely filled in with loam with grass seed freshly spread on the soil that had been dumped in place by a dump truck. There was a large geotextile covering half of the newly deposited soil. After attempting to inspect the mound, I was told to stay off the mound by construction workers, who had parked their vehicles on the top of the mound. Construction and crew workers were parking vehicles on top of the smaller mounds, not to mention very large backhoes parked on the top of the mounds. According to Paula Cross, they were only supposed to remove the previous repair fill - and not impact the mound fill. But they went over a meter deep through a 50 ft wide and 50 ft long area. I calculated the volume of removed moundfill to total 30,000 cubic feet based on measurements of the piled up dirt south of the silos that are between Monks Mound and Woodhenge. The IHPA gave site directors permission to repair the damage. The depth of the excavations may have been caused by accidental removal of too much soil. However, a contractor should know that when digging into an archaeological site, the permits must be followed exactly. After a circle of limestone slabs and cedar posts had been hit by the backhoes, Tim Pauketat, an archeology professor at the University of Illinois stopped this excavation and expressed his unhappiness with the work (according to the IAS newsflash website).
The site management told me that "as long as its ripped wide open" then we should salvage what we can find. So they hired archaeologists to look at the profiles of the excavations for a few days. During this time, there were drawings made and measurements taken of the exposed features. However, "as long as it's ripped wide open" was illegal and should never have happened. Foremost for the reason that it is a desecration of sacred burial mounds.