The Research Council of Alberta stratigraphic corehole near Castor, Alberta (RCA Castor 13-34-37-13W4) was cored to a depth of 181.7 in (596 ft.) in 1967. The corehole was spudded in the basal Horseshoe Canyon Formation and continued into the top of the Dinosaur Park Formation. Fifty-six samples were studied for palynology and 44 stratigraphic levels were sampled for magnetostratigraphy. An additional 3 outcrop samples were taken for magnetostratigraphy near Castor to supplement an interval of no recovery in the core.The recovered palynomorphs and their relationship to the magnetostratigraphy support regional correlations developed previously for the Red Deer Valley to Cypress Hills area of southern Alberta. The close magnetostratigraphic correlation between the Castor core and Red Deer Valley sections has enabled the recognition of polarity subchrons 32n.5n to 33n.3n in the Castor core. A hiatus of some 0.3 m.y. occurs below the Horseshoe Canyon Formation in the Castor core. The base of the Horseshoe Canyon Formation is shown to be a little younger in the Castor area than in the Red Deer Valley (32n.6n vs. 32r.1r), suggesting progradation from the west rather than northwest. The Second Castor Sandstone correlates to the Dorothy Sandstone of the Red Deer Valley.