URUSHIBARA Kazuko Faculty of Literature, Komazawa Univ., Prof., 文学部, 教授 (00101329)
TOMIKAWA Akeo Inst.Applied Biochem., Univ.of Tsukuba, Assistant., 応用生物化学系, 助手 (90015660)
HIGASHI Teruo Inst.Applied Biochem., Univ.of Tsukuba, Assoc.Prof., 応用生物化学系, 助教授 (20094170)
|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1994 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1993 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1992 : ¥1,000,000 (Direct Cost : ¥1,000,000)
The rate of formation of red soils developed on the raised coral limestone terraces in Kikai Island and Minamidaito Island was estimated by using the mean rate of techtonic uplift and the glacioeustatic curve during the late Quaternary. The results obtained are as follows :
The state of rockland continues for about 1,500 years after the emergence, and it takes about 3,000 years to develop Lithosols. Initial Rendzina-like soils (Rendzic Leptosols, Lithic Rendolls) begin to develop after 3,500-3,900 years, and the soils of 35,000-40,000 years are Rendzina-like soils (Rendzic Leptosols, Lithic Rendolls). The soils of 50,000 to 55,000 years of age are changing to Brown Rendzina-like soils (Mollic Leptosols, Eutropeptic Rendolls).
They develop into Terra fusca-like soils (Haplic Luvisols, Typic Hapludalfs) in 70,000 to 80,000 years. After 95,000-100,000 years from the emergence, rubefaction proceeds and the soils become to Terra rossa-like soils (Haplic Lixisols, Typic Hapludalfs). The soils of 120,000-125,000 years of age have an intermediate properties between Terra rossa-like soils and Red-Yellow soils (Haplic Lixisols, Typic Hapludalfs). Therefore, it is concluded that it takes at least more than 125,000 years for Red-Yellow soils (Acrisols, Hapludults) to develop on coral limestone under sub-tropical conditions.