One hundred and thirty five surface-collected specimens were analyzed from sites in the vicinity of Kobom (Airati, NGRP 25, 28, 32, and 33), inland from Aitape.
In comparison, the highest frequency of New Britain obsidian from any dated context in the Aitape region is 10%, in the units containing Wain style sherds at NGRP 46.
Though present in low frequencies in 'early' assemblages, the frequency of Pare Lin obsidian increases after ~2000 calBP, and appears to peak in frequency during the Sumalo phase, but then becomes progressively less frequent in the Aiser and Wain levels at NGRP 46.
Wekwok obsidian appears to follow a similar trend, though its frequency peaks in the Aiser levels at NGRP 46.
Preliminary comparison of the Nyapin levels at NGRP 46 with Tarawai Sareta and Simindibubu, and the Sumalo levels at NGRP 46 with Aitape area assemblages suggests that interesting site by site and regional differences may exist, however.