 Dissolved aluminum and iron may also move downward in inorganic forms and be deposited as aluminum-silicon complexes and iron oxides.An Ae (light grey, strongly leached) horizon usually overlies the Podzolic B horizon.Podzolic soils occupy about 1 429 000 km2 (15.6%) of Canada's land area and are dominant in vast areas of the humid Appalachian and Canadian Shield regions and in the humid coastal region of British Columbia.