Paired-post Screen
During the excavation of Mt. Horeb, archaeologists uncovered the remains of a structure that Adena people built and used prior to digging the ditch. The structure consisted of a circle of paired posts. Average post diameter was just under a foot. There was no evidence that the builders wove smaller saplings between the posts to create a solid wall. Thus, it may have looked more like a circular standing screen than a walled circular structure.
Archaeologists think that Adena paired-post structures were open-air meeting spaces where groups held important ceremonies. The circular screen would have set up a boundary around this ritual space, limiting access to only those people directly involved in the ceremonies.
However, since the structure sat on a prominent place on the landscape, people excluded from the ceremonies still would have known that an important ritual was underway. Imagine attending an evening ceremony, looking up at the circular structure and seeing the flicker of torch light through the paired posts.
With the construction of the ditched enclosure, the paired-post structure was no longer needed. The outer walls of the embankment would have served the same purpose - effectively separating certain people from the events taking place within the enclosure.