The platform mound located at the site was described in 1975 as being in the shape of a truncated cone approximately high and with a base in diameter. On the eastern edge of the mound in the central area of the site was a plaza surrounded by domestic structures making up an oval shaped village of 2.13 hectares.
Mound
Platform mounds are built up in a series of stages that can span generations. The Dyar mound itself began during the Stillhouse Phase with a large civic structure with a sand floor and built with single set post construction. Over this a layer of thick blue-black clay was added. On top of this was added a layer of grey clay loam and on which another structure was added. Stillhouse Phase Etowah Complicated stamped pottery sherds were found at this layer. Stage II begins with another layer of grey clay loam added. Stages III, IV, V, and VI are in sequence of dark and then white clay, red and grey clay, of grey and tan clay, and of dark grey and reddish tan clay, each stage with its own structure. Stage VII consists of of grey and orange and of yellow clay. A step up on the western side of the summit indicates that this stage was the first to have multiple levels and multiple structures, possibly two large structures on the western side and a smaller one on the eastern side which was found to have had a burned floor. Stage VIII was a layer of brown clay to thick. The eastern side at this stage is lower than the western side and covered by a layer of construction debris though to have come from the razing of an old structure on the western side. Stage IX is of brown and grey clay with the multiple levels continuing. Pottery sherds from this layer are thought to date from the Duvall Phase. Stage X is a thin layer of light grey clay followed by Stage XI which is another thick layer of gray and tan clay. Stage XI is thought to date from the Ironhorse Phase. All stages above this date to the Ironhorse and Dyar Phases. Stage XII is a layer of yellow and grey clay. The structure at the western side has a semi-subterranean floor cut into its surface, the first seen on the mound. At this stage the difference between the eastern and western levels is to. Stage XIII was a layer of yellow-orange and grey clay. The eastern level has a to cap of yellow clay. This stage and Stage XIV, an indeterminate layer of gray sandy clay, were not found to have structures. It is not known if they did not have structures at this time or if the evidence for these structures or subsequent layers has been lost.
Mound structures
The western level from stages VII to XIII had two large structures with specially prepared clay floors that were kept meticulously clean. The floors on these structures was very deeply entrenched into the mound. This feature was noted by the first European observers of the mound. Without the structures over them, they assumed the deep enclosures were walls. The two structures may at times have been connected by a passageway, although this is not certain. It is also not certain if all stages had both structures. These structures were also rebuilt multiple times during the last phases of construction, more often than the layers of new mound fill were added. The function of northwestern of the two cannot be determined, but the southwestern structure has archaeological remains relating to ritual activities such as the sacred fire and the black drink ceremony. The final structure at the southwestern position was burned and radiocarbon dating of its remains have placed it at 1555. The eastern structure was domestic in nature and was used for food preparation, cooking and possibly feasting. Except for a short time in the 14th century the Dyar mound and its accompanying structures were regularly rebuilt for over five centuries.
Site chronology
Archaeologists use changes in ceramic styles across multiple sites to determine timelines for entire regions. The ceramics found at the Dyar site show that it was abandoned for a time during the Scull Shoals, but was again inhabited from the Duvall Phase 1375 - 1450 until the time of European contact.
Excavations
While the mound had been described as early as the late 19th century, by C.C. Jones, and subject to undocumented amateur excavations, it was not systematically researched until 1975 when, in a project funded by the Georgia Power Company, it was excavated by a team led by Chester DePratter of the University of Georgia. Although hampered by damage done to the mound by amateurs, DePratter's research found it unique to the area, concluding that it was a large Lamar mound and village site. In other areas, soil evidence indicated plowing from the 19th century and poor farming practices in the area that century and the next. The area does not seem to have been the home of one group or people following one leader. Rather, evidence supports four phases of native occupation, ranging from 1100 to 1600: The Stillhouse phase, the Duvall phase, the Iron Horse phase, and the Dyar phase. Variance in ceramics are a strong indicator of the different phases. Pottery suggests that the area was occupied in the Stillhouse phase by people of the Etowah chiefdom. In the 15th century, after a period when the site was unoccupied, the region seems first to have been settled by Lamar people, as some Lamar artifacts were discovered in those remains. The final two phases are also Lamar occupancy, terminating in approximately 1555. Contact with Europeans may have led to the gradual abandonment of the mound.
