Palaeosols may: be found in almost every stream valley in southern Alberta. Humic acids from Ah horizons of palaeosols from five locations were examined by infrared spectroscopy, and the percentage of opal phytoliths in the coarse silt (20 to 50 μ) fraction was determined.The combination of the character of the infrared spectra of humic acids and opal phytolith counts was helpful in explaining the genesis of the palaeosols of the five locations. Sometimes the presence or absence of evidence of human occupation will add to the interpretation. In the locations examined, grasslands apparently have been dominant during post-glacial times with invasions of trees, such as Populus spp. and Salix spp., in the moister and more sheltered riparian habitats in this area. Any of these invasions naturally led to a transformation of these grassland soils.