Geological models that aid in the understanding of buried valleys are a product of recent studies in the Oak Ridges Moraine (ORM) (e.g., Barnett et al. 1998; Sharpe et al. 2002a; Russell et al 2003a; Logan et al. 2005). This work has contributed an emerging robust geological framework, yet these data have not been analysed in the context of the Laurentian valley system and its evolution over time. In contrast, conceptual hydrogeological models that might provide a framework for Laurentian valley aquifers (Fig. 1) a