Figure 4. Cross-Nichols photomicrographs. A. Void-filling argisepitubule soil microfabric (highly birefringent material in center of micrograph) in a Bt horizon from a Type E paleosol (Argillisol) that formed after an airfall tuff. Field of view is 2 mm across. B. Void-filling argilstriotubule soil microfabric in a mudstone matrix from a Bt horizon in a Type E paleosol (Argillisol). Opaque areas in mudstone matrix are hematite-rich grains. Field of view is 5 mm across. C. Latticesepic soil microfabric in a Type D paleosol (Vertisol). Field of view is 0.5 mm across. See text for discussion. D. Oosepic soil microfabric in a Type C paleosol (Gleysol). Field of view is 2mm across. See text for discussion. E. Sphaerosiderite concretions in a silty claystone from a Type C paleosol (Gleysol). Field of view is 15pmm across. F. Blocky siderite crystals from the mineral horizon of a Type B paleosol (Histosol). Field of view is 0.5 mm across.