Geoarchaeological Investigation of Agricultural Terraces in Pualaulau, Hālawa Valley, Moloka‘i, Hawai‘i

Abstract

Agricultural systems on islands provide good case studies for studying landscape modification, resource allocation, and the potential sustainability of these systems. The Hawaiian Islands offer a unique environment for analyzing how geomorphological constraints shaped landscape modifications, creating environmental legacies that were further developed under specific socio-political systems. This study investigates the archaeological remains of a terraced agricultural system in the ‘ili of Pualaulau in Hālawa Valley, Molokai, posing the question of whether the terraces were formerly irrigated. The location of the terraced agricultural system is slightly northwest of what today is an intermittent stream. Past climate data suggests that seasonal rainfall may have allowed for potential irrigation of the terraces during the rainy season. Varying levels of seasonal rainfall suggest that this terrace system could have been seasonally irrigated, diversifying its uses for potential year-round cultivation. Geoarchaeological methods are used to determine 1) whether terraces within the designated dryland agricultural system were potentially seasonally irrigated, and 2) how frequently seasonal irrigation was used in this terrace system. Particle size analysis (PSA) and an assessment of sediment particle angularity are used to determine the origin and mode of deposition of sediment particles within the terraces. Samples from a natural colluvial slope, from known dryland terrace systems, and from the adjacent streambed serve as controls for samples collected from the agricultural terraces. Utilizing established agricultural systems, like the side-stream terrace systems of Pualaulau and Kapana, for permanent or seasonally irrigated agriculture demonstrates the adaptability of early Kanaka Maoli working and living in Hālawa Valley. As populations continued to grow it was necessary for these populations to adapt to seasonal changes in natural resources, to better support their communities.