The average abundance of fluorine in the earth's crust is rather plentiful than that of chlorine, but the average concentration of fluoride in natural water is very low as compared with chloride. Fluoride is well known to produce strong teeth mottled in children raised where the fluoride concentration of water supply is above the recommended limit. In Japan, the limited value for drinking water is settled for 0.8 mg/i. In other respects, the concentration of fluoride more than 2 mg/kg is adopted as one of the criterion for mineral water which discriminate between normal water and abnormal water. In this paper, five case studies, all from Kinki District, have been chosen to discuss how the high fluoride groundwater is formed.
In the case of Rokko granitic area, south-eastern part of Hyogo Prefecture, the possible origin of fluoride in water is due to the presence of high fluorine biotite in the rocks. The Paleozoic sandstone and shale in the northern part of Osaka Prefecture, Hokusetsu area, frequently contain high fluorine through contact metamorphism. The wells drilled in these rocks yield high fluoride water. As for these cases, high fluoride water often accompanies with high pH. Some leaching experiments using granitic rocks result in a similar relation between fluoride concentration and pH. The fluoride ion can be bounded to mineral in place of hydroxyl ion, so that with increasing pH it can be displaced from this site by hydroxyl ion in solution.
A few cases of high fluoride stratum waters are reported in this area. It is not clear that the waters are caused by the geological structure which permits the upward flow of groundwater in a basement rock, or by the presence of fluorine-bearing-minerals in the stratum. More detailed researches are required in the case of stratum water.

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The author is reporting of several findings, resulting from the author's experiment of structure and water permeability of shallow layer at zero order channel basin in the Tama Hill(Fig. 1).
From the results of tests at the broadrige except at the spur, it has been shown that the residual soil zone runs almost parallel to the land surface and makes almost the same thickness. On the downstream from the nick point, it has been proved that the valley-bottom is formed by transported soils(Fig. 5, Fig. 6).
At the residual soil zone, it was found that the permeability coefficients of the upper soil layer are larger than those of tije lower soil layer and the permeability coefficients of the upperstream are smaller than those of the downstream.
Moreover, at the thalweg in this drainage basin, the strongest correlation was observed between field permeabilities and altitude differences. The correlation coefficient at the upper soil layer is 0.937 and at the lower soil layer is 0.918 except for the remarkable difference of.*1 and(Fig. 7).

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