Shoutout to the team at the Cahokia dig site for letting me try their new ground-penetrating radar unit last month, because my first scan over what looked like a regular field edge near Mound 72 showed a massive, unexpected void pattern about 15 feet down that could be a whole new structure.

Has anyone else had a GPR reading that looked too good to be true, and how did you verify it without disturbing the site?

2 comments

2 Comments

marymorgan13d ago

That's a solid idea from @simonw41. We've done something similar but paired it with a small-diameter bucket auger right after the probe. If you hit that void, you can pull up a tiny, clean column of whatever is filling the space. Seeing the full soil layers in order, even from just a couple inches wide, can tell you if it's a dug feature. It's way less damage than a test unit and gives you real dirt to look at. Just gotta be super careful to log the exact spot and depth.

simonw4113d ago

Ever try a small soil probe to get a sample from the exact depth of the anomaly? You can sometimes feel a change in resistance or bring up material that tells you what's down there, like bits of charcoal or different soil color, without any real digging. It's a low-impact way to check if the void is filled with something like an old storage pit or just a natural feature.