Clay minerals of sediments in the Yatsushiro bay

Since three decades ago it has been established by numerous investigators⁴,⁷,⁹⁾ that the general Process of formation of clay minerals is different between the marine and terrestrial conditions, and that the clays of the marine origin are, in general, of illitic type, whereas those of the terrestrial are of kaolin group. In previous communications,¹,²⁾ it was reported that clay fractions of the soil and mud from the Ariake Sea are characterized by the abundance of minerals of illite-montmorin series (montmorin refers to montmorillonite group after Jackson and Sherman⁸⁾, being different from most terrestrial soils in Kyushu. The matter seems to be of some importance because the Presence of montmorin, even in a relatively small quantity, is likely to exercise a considerable, influence on the behaviour and properties of the clay and the fertility of the soil. The soils of the reclaimed land of the Sea are not only productive, Whether they are clayey or sandy, but also they have been approved to be powerful improving materials for the degraded paddy soils, so-called “Akiochi” soils by several field experiments.