Pea Sijajap is at about 100 m lower altitude in the Simamora rift. “Pea Sijajap is a small, almost totally infilled volcanic crater, but it is at about  1300 m altitude in a downfaulted rift valley, not on the plateau. At the time of  coring, a very small area of unreclaimed herbaceous swamp existed at the center  of the site, surrounded by wet-rice fields and low scrub vegetation on dry land  beyond that. Four radiocarbon dates have been obtained from the upper 1.15 m  of the short core, but the uppermost one is inverted.”
The age of the peat is between 20,000-30,000 years. This is 3 times older than lowland coastal peatland in Riau, which was dated to be 6500 years BP.