The number, form and origin of sub-horizontal surfaces in north Ceredigion, Wales, UK

The number, form and origin of a stepped sequence of sub-horizontal surfaces in north Ceredigion, U.K., has been the subject of continuing controversy over nearly two centuries of investigation. Renewed impetus to re-examine the evolutionary geomorphology of the area is provided by a number of parallel advances within associated earth science disciplines. Using traditional geomorphic research techniques, data are presented from the interrogation of a Digital Elevation Model (DEM) to constrain the number and form of the sub-horizontal surfaces in the region. Altitude-frequency histograms identify tilted sub-horizontal surfaces elevated at between 81-270, 221-440 and 431-540 m asl, whereas topographic profiling techniques demonstrate that a tripartite division is no more applicable than that of a single concave surface for the characterization of the landscape. It is suggested this observed tripartite arrangement has developed from an initial single uplifted concave surface. The origin of the surfaces is considered within the context of regional geomorphic inheritance and continental deformation. A model of landform morphogenesis is proposed that considers all relevant geomorphic lines of enquiry; the importance of adopting an integrationist ethos in studies of evolutionary geomorphology is stressed.