Calcarenites occur at several horizons in the lower part of the Ringerike Group (Sundvollen Formation) at Ringerike. Analysis of cross-stratification, composition and grain-size distribution enables the calcarenites to be interpreted as shallow marine deposits which formed near the mouths of large tida! estuaries. It is suggested that sedimentation in 'Stage' 9 was taking place to the south of these estuaries and that the calcarenites were derived from previously lithified carbonates in that area.