The iron and aluminium oxides collect in the 'B' horizon where the iron oxides can accumulate to form a thin layer of hardpan, which impedes drainage through the soil. Illuviation is the process ...

as workers lay the first layers of soil on the overpass. The Wallis Annenberg Wildlife Crossing spans the 10-lane freeway in Agoura Hills and will become the largest such crossing in the world.

as workers lay the first layers of soil on the overpass. The Wallis Annenberg Wildlife Crossing spans the 10-lane freeway in Agoura Hills and will become the largest such crossing in the world.