Rocky shorelines are commonly punctuated, with alternating high relief cliffs and incised embayments which host “pocket beaches”. While multiple cases of ancient rocky shorelines associated with low relief ravinement surfaces have been documented in the geological record, deposits formed in pocket beaches and joint-cut coves are more rarely described. This poses the question “are high relief rocky coastlines and their associated deposits not preserved or have they been previously overlooked? Here we document exhumed examples of ancient granitic rocky shoreline systems of diverse morphologies from the Early Miocene of northern Austria, and compare them with modern systems in UK, Corsica, Spain and Norway. The preserved ancient examples offer a good opportunity to characterize these sedimentary systems, provide diagnostic criteria for their recognition and discuss the main controls on their occurrence and preservation in the rock record. From their stratigraphic and sedimentological analysis, and its comparison with modern examples, we interpret that these rocky shorelines form and get preserved during rapid rates of combined tectonic and eustatic sea-level rise, along lithological, structural and weathered “weakness” zones affected by normal low wave energy conditions interrupted by storms. These results provide a mechanism for predicting their potential occurrence and distribution during transgression of rocky coasts, with implications for exploration around structural highs and coastal management.
Bibliographical noteFunding Information:
We gratefully acknowledge the Norwegian Research Council (grant agreement 295208 ) and the companies Equinor, Lundin, Spirit Energy and Aker BP for sponsoring the Suprabasins project where this research is englobed. We would also like to thank the Hengl Company for allowing the fieldwork in the Limberg Quarry. Thanks to the editor-in-chief Dr. Catherine Chagué and two anonymous reviewers for their useful comments which have improved the content of the manuscript.
Data Availability StatementData will be made available on request.
- Granitic basement
- Joint-cut coves
- Pocket beaches
- Rocky shorelines