Thick gray, cemented subsoils occur commonly at depths of 50–75 cm below the mineral surface of soils in humid southwestern B.C. They are impermeable to roots and have hydraulic conductivities of about 0.1 to a few millimeters per hour. Dense, moderately coarse-textured basal till is the most common parent material, but such cemented subsoils also occur in some fluvial deposits. The degree of cementation varies from weak to strong and cementation decreases gradually with depth. These subsoils differ from fragipans in several respects: air-dry clods do not slake in water; they remain hard on wetting; they may occur in coarse-textured deposits; they are apparently chemically cemented. Unlike orsteins they are not brown and they are not obviously cemented by iron compounds. Results of slaking experiments and extractions with various reagents indicate that the cement may be amorphous materials containing varying proportions of Al, Si and Fe. The strongly cemented subsoils are designated as duric horizons in the Canadian System of Soil Classification and duric subgroups of Podzolic soils are identified. Taxonomic problems remain, however, as there is a continuum of degrees of cementation in subsoils, and some duric horizons occur in Brunisolic soils. Duric horizons are clearly of significance to most use interpretations of soils.