Adelinet,M., Fortin,J., d'Ozouville,N. and Violette,S.(2008): The relationship between hydrodynamic properties and weathering of soils derived from volcanic rocks, Galapagos Islands (Ecuador). Environ.Geol., 56, 45-58.

『ガラパゴス諸島（エクアドル）の火山岩由来の土壌の流体力学的性質と風化との関連』

『Abstract
　The aim of this interdisciplinary study is to examine a component of the hydrological cycle in Galapagos by characterizing soil properties. Nine soil profiles were sampled on two islands. Their physical and hydrodynamic properties were analyzed, along with their mineralogical composition. Two groups of soils were identified, with major differences between them. The first group consists of soils located in the highlands (＞350 m a.s.l), characterized by low hydraulic conductivity (＜10-5 m s-1) and low porosity (＜25％). These soils are thick (several meters) and homogeneous without coarse components. Their clay fraction is considerable and dominated by gibbsite. The second group includes soils located in the low parts of the islands (＜300 m a.s.l.). These soils are characterized by high hydraulic conductivity (＞10-3 m s-1) and high porosity (＞35％). The structure of these soils is heterogeneous and includes coarse materials. The physical properties of the soils are in good agreement with the variations of the rainfall according to the elevation, which appears as the main factor controlling the soil development. The clayey alteration products constrain soils physical and hydrodynamic properties by reducing the porosity and consequently the permeability and also by increasing water retention.

Keywords: Physical soil properties; Hydraulic conductivity; Mineralogical composition; Galapagos Islands』

Introduction
Material and methods
　Study area
　Study site
　Determination of the clay fraction
　Hydraulic conductivity in situ measurements
　Porosity measurements
Results
　In situ and laboratory results
　　Hydraulic conductivity measurements
　　Porosity measurements
　X-ray diffraction results
　　Results from samples extracted on the surface
　　Results from samples extracted at depth (more than 20 cm)
Discussion
　Soil physical properties versus altitude
　Effect of the clay fraction on the physical properties of soil
　　Clay minerals composition
　　Porosity versus prescribed air humidity
　　Relationship between porosity and permeability
　Hydrological implications
　　Differences between Santa Cruz and San Cristobal
　　Implications for surface runoff and infiltration areas
Conclusion
Acknowledgments
References

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