Cosmogenic exposure dating reveals limited long-term variability in erosion of a rocky coastline

Abstract

Predicted sea-level rise and increased storminess are anticipated to lead to increases in coastal erosion. However, assessing if and how rocky coasts will respond to changes in marine conditions is difficult due to current limitations of monitoring and modelling. Here, we measured cosmogenic 10 Be concentrations across a sandstone shore platform in North Yorkshire, UK, to model the changes in coastal erosion within the last 7 kyr and for the first time quantify the relative long-term erosive contribution of landward cliff retreat, and downwearing and stripping of rock from the shore platform. The results suggest that the cliff has been retreating at a steady rate of 4.5 ± 0.63 cm yr −1 , whilst maintaining a similar profile form. Our results imply a lack of a direct relationship between relative sea level over centennial to millennial timescales and the erosion response of the coast, highlighting a need to more fully characterise the spatial variability in, and controls on, rocky coast erosion under changing conditions.

Multi-objective optimisation of a rock coast evolution model with cosmogenic <sup>10</sup>Be analysis for the quantification of long-term cliff retreat rates

“…Model predictions of CRN concentrations across a shore platform display a characteristic "humped" distribution profile across-shore (Hurst et al, 2017), for which the magnitude of the hump is inversely proportional to cliff retreat rate (Regard et al, 2012). Previous applications of CRN measurements to cliffs and shore platforms have been used to quantify cliff retreat rates (Duguet et al, 2021;Hurst et al, 2016;Regard et al, 2012;Rogers et al, 2012;Swirad et al, 2020), understand Quaternary-scale shore platform exposure history (Choi et al, 2012), date major mass-wasting events (Barlow et al, 2016;Recorbet et al, 2010), and constrain shore platform denudation rates (Raimbault et al, 2018). Combining CRN analysis with a coastal evolution model can help reveal site-specific, long-term cliff retreat and shore platform lowering rates (Trenhaile, 2018).…”

Rock coast erosion: An overlooked source of sediments to the ocean. Europe as an example

“…Today, cliff-retreat rates mostly come from non-weathered cliff erosion (Prémaillon et al, 2018). We can vouch for this assertion based on the millennial retreat rates calculated from 10 Be cosmogenic nuclide (Regard et al, 2012;Hurst et al, 2016;Swirad et al, 2020;Duguet et al, 2021). These millennial rates are either similar to estimates of the current retreat rate (Regard et al, 2012;Swirad et al, 2020) or lower, indicating a recent and gentle acceleration, probably caused by human activity (Hurst et al, 2016;Duguet et al, 2021).…”

Tracking the behavior of rocky coastal cliffs in northwestern Spain

“…It has been suggested that cliff erosion rates will increase due to rising sea level and possibly increased storminess (Dickson et al 2007;Ashton et al 2011;Trenhaile 2011Trenhaile , 2014aGómez-Pazo and Pérez-Alberti 2017;Limber et al 2018), but the data from hard rock coasts are, at present, ambiguous and contradictory (Lee et al 2001;Hurst et al 2016;Young 2018;Swirad et al 2020). There is little evidence that apparently increasing rates of recession in the study area were triggered by increases in wave height or precipitation, and it is questionable whether such a marked increase in rates could be attributed to an approximately 0.06 m rise in global sea level from 2002 to 2018 (Table 4; Fig.…”