BOULDER BEACH GEOMORPHOLOGY: AN INVESTIGATION IN WESTERN IRELAND

Boulder beaches are under-studied archives of ocean-coast interactions. As climate warming fuels sea level rise as well as increased storminess, and as coastal infrastructure and marine energy projects proliferate, the intricacies of shoreline morphodynamics become more important to understand. We compiled data from 23 boulder beaches in western Ireland, including clast dimensions and beach profiles. The beaches represented varying topographic settings and ocean exposure, and clast sources include both bedrock and glacial till.

Preliminary analysis reveals several statistically significant (p < 0.05) relationships. We found that wider beaches tend to have larger boulders as well as shallower beach face slopes, and that these variables are also correlated with the height of beach-backing till cliffs. Beaches without a till cliff tend to be narrower, with well-developed steep boulder berms. These observations suggest that retreat of unconsolidated till cliffs supplies boulders at a faster rate than they can be reworked and broken down in the beach environment. This interpretation is strengthened by examination of published wave power maps, which indicate that wider beaches are also associated with lower wave power flux.

While this preliminary bivariate yields valuable and promising results, it is clear that multiple interacting factors influence boulder beach dynamics, which we plan to investigate using non-parametric multivariate analysis.