Finally found why my excavation photos were all wrong

Kept seeing people tag post-holes as 'hearth features' in their field reports. I checked the soil samples from my dig in Colorado last summer and the charcoal layers were way too shallow - a real hearth leaves a distinct thermal signature about 8 inches deeper. Anyone else run into this misidentification problem at your sites?

2 comments

2 Comments

kelly.keith6d ago

The charcoal layer issue is a good clue, but I've also noticed that real hearths leave a specific orange-red baked clay ring around them, not just charcoal. At a site in New Mexico last fall, we found a cluster of those shallow charcoal spots that everyone called fire pits, but they turned out to be from a single lightning strike that burned a tree root network. That thermal signature you mentioned is key, but you also have to check for magnetic susceptibility changes in the soil, because a real hearth will show a clear spike in that reading even if the charcoal is gone. Did you run a magnetometer over your samples to confirm the depth?

xenan646d ago

My buddy in Colorado tried that and his magnetometer readings were all over the place, @kelly.keith.