Fig. 6. Micrographs of polished blocks from Bt horizon: (A) 50-cm depth, (B) 55-cm depth, (C) 48-cm depth, and (D) undyed soil at 55-cm depth showing structural voids plugged with clay and Fe oxides (arrow); d = dye-stained soil, u = undyed soil, f = fecal material, v = voids. Bar length = 5 mm.