GEOGRAPHY OF SOIL FORMATION AND WEATHERING ON VOLCANIC ISLANDS OF THESOUTHWESTERN PACIFIC-OCEAN

This paper identifies the regular features of the geography of soils o n volcanic ash under conditions of the humic tropical climate of the i slands of the southwestern Pacific Ocean. The soil geography is govern ed by the different duration of the processes of soil formation and we athering. Four stages of self-development of the volcanic ash soils ha ve been identified, which correspond to the following types: Primitive Layered-Ashy, Layered-Ashy Allophanic, Brown Eutrophic, and Red-Brown Clay-Differentiated soils. The time intervals for the formation of th e profiles and the development of processes of humus accumulation, wea thering, structurization, suspension transport, and illuviation have b een established. It is shown that the soil of humid regions of volcani c islands of the southwestern Pacific Ocean is represented to a signif icant extent by immature soils, and their geography is determined by t he different duration of the processes of soil formation and weatherin g, that is, by the heterochronicity of the ash.