Fig. 4

Spatial distribution of the calibrated ages obtained around the basal horizon of peat layer. Red, orange, yellow, greenish yellow, green, and aqua colors are ages obtained from the deposit of peat swamp forest, indicating over 6000 cal BP, between 5999 and 5000 cal BP, between 4999 and 4000 cal BP, between 3999 and 3000 cal BP, between 2999 and 2000 cal BP, and between 1999 and 1000 cal BP, respectively