[6] The site shows evidence of human occupancy from the peak of the Hypsithermal era, approximately 7,000 years ago.
[6] The shallow water level of the marsh, the clay loam, and the basalt rubble basin extended all around and over this area afforded only a weak foundation for settlement.
The lower stratum is lacustrine, waterway diatom-rich silt from the original lake floor present during the first occupation of the site.
[17] Stone anvils from the excavation had single and bilateral worn out pits used for knapping the obsidian to break the spalls from the rock.
[18] The large amount of anvils found on Nightfire Island suggest they were used for other purposes than knapping, including cracking bones.
[21] An increase in small, stemmed and corner notched arrowheads have been discovered on layers of approximately 2,500 years BCE which corresponds to the peak in the dabbling duck remains and the adoption of the bow and arrow.
[4] A higher than usual frequency of neuronal malformations in remains discovered within Nightfire Island suggest tentatively that inbreeding might have occurred.
[22] Studies of skeletal remains also revealed an unusually large and deep fossae lateral in the 1st and 2nd sacral tuberosities, suggesting a very strong postural ligament attachment.
While rainfall was not consistent, the alkali open marshes held in place by block-fault ridges provided a rich habitat for local and migratory waterfowl.
Nightfire Island soils didn't contain egg shells,[27] however residents took advantage of bird-nesting season for the stability of their life cycle.
Analysis of samples from Nightfire Island show that residents ate a great variety of birds: Podiceps spp., Cygnus spp., Branta spp., Anas spp., Aythya spp., Bucephala spp., and Mergus spp.