Abstract
Clay mineral composition of the Holocene soils in the narrow basin of Hattori river, Imadate, Fukui, Central Japan, was compared with that of the Miocene soils on the surrounding hill by means of XRD, DTA, TG and chemical analyses. The results led to a following conclusion:
Smectite in the Holocene soils of this basin hardly originated in the Miocene sediments located at both side hills, but in the Miocene ones at the upper stream of Hattori river. This smectite was derived directly from parent materials. Or it was altered secondarily from vermiculite or its related minerals, which had been formed previously in the Miocene soil located at the upper stream, in the Holocene soil exposed alternately to the reductive and oxidative conditions. Smectite in this Holocene soils inside of this basin was brought from the Miocene materials in the upper stream, in either case.
