Hawaiian Quaternary Paleoenvironments: A Review of Geological, Pedological, and Botanical Evidence.

Abstract

Climates in Hawaii during glacial periods were relatively wetter and cooler than interglacial climates. Eolian deposits indicate that northeasterly trade winds predominated during glacial periods. Orographic rainfall patterns were probably similar to those of today except that they were shifted downward in response to lowered sea levels and a depressed inversion level. Botanical evidence indicates that some areas probably received more than double their current annual rainfall. Greater rainfall during glacial periods was probably responsible for the formation of highly weathered soils that are now in semiarid climates. More intense periglacial processes may have operated during glacial periods. Snowline on Mauna Kea was depressed about 900 m and glaciation may have occurred because of lower air temperature and greater cloudiness. Ocean temperature was probably also slightly cooler. At low elevations, interglacial climates were drier than glacial climates because of the influence higher sea levels had on orographic rainfall distribution. Trade winds still predominated but the inversion level was higher, which may have caused greater rainfall at high elevations. Pedological evidence indicates a highly erosive environment before the formation of the Kaena shoreline at about 650,000 yr ago. Climatic conditions at that time are not known. Subsequent environmental conditions have not been as conducive to erosion, and the past several hundred thousand years have witnessed relative landscape stability.