The soil survey of the Chanthaburi study area was conducted and covered an area of approximately 2870 sq km (1108 sq mi). Reconnaissance was made along all accessible roads and trails. Soils were studied at road cuts and at exposures along drainage channels. In areas of good accessibility, borings and profile pits were made in order to study the soil in greater detail. An average of about 15 observations per square kilometer was recorded. Detailed field data were mapped on airphotos at a scale of 1:40,000 then transferred from the airphotos to Series L 708, Army Map Service topographic maps at a scale of 1:50.000. Unfortunately, the airphotos were made in 1953 and considerable development has taken place in the study area since then.