Reconstructs the palaeoenvironment during the period 3500 B.C. to the end of the prehistoric period. Freshwater molluscs found in prehistoric layers suggest that the first occupants of Ban Chiang encountered a habitat with permanent lakes and clear, slow moving streams. Since the lakes contracted in the dry season, there were ideal conditions for practicing wet swidden agriculture. From <i>c. 1600 B.C. the presence of water buffalo and associated changes in the faunal spectrum suggest the inception of wet rice cultivation. -- AATA