"Open Air" Sites
All the sites explored to date are what archaeologists term “open air” sites, as opposed to “stratified” or layered sites. This means that sites at Mount Vernon were exposed to natural processes of weathering and erosion for thousands of years.
Think of the difference between an open field and a cave. Archaeological features such as ash from a campfire will disappear in the exposed field over time, whereas it could accumulate in the protected environment of a cave. For this reason, we have not used techniques like radiocarbon dating to precisely assign a “year” to our sites here at Mount Vernon.