Rock control on the shape of coastal embayments of north-western Hornsund, Svalbard
Swirad, Zuzanna M.; Migoń, Piotr; Strzelecki, Mateusz C.
published: Apr 1, 2017
published online: Jan 1, 2017
manuscript accepted: Oct 24, 2016
manuscript revision received: Oct 21, 2016
manuscript revision requested: Oct 4, 2016
manuscript received: Jul 22, 2016
ArtNo. ESP022006101002, Price: 29.00 €
Abstract A 17.6 km section of coastline in Hornsund, SW Svalbard is analysed to assess the role of geology in shaping rocky coasts at the macro-scale (100s m to km), with the focus on headland/embayment alternation. The study combines geomorphometry to quantify coastline shape, analysis of lithological variation, strike and dip, all derived from detailed geological maps, and results of rock strength determinations in the field (Schmidt hammer R-value) and through laboratory tests (Point Load Strength Index). The plan-view shape of the coastline is characterized by form factor, sinuosity index and coefficient of asymmetry. Lithology and structure are dominant controls and generally, more diverse lithology translates into more diverse coastline, highlighting the role of selective erosion. Numerical values of form factor (embayment depth/width) and sinuosity index are the highest when bedding is parallel to general coastline outline. Absolute embayment depth increases with growing number of lithological boundaries intersecting the coastline. Cliff retreat in weaker rocks appears more uniform, resulting in less indented coastline. From methodical point of view, we suggest that in foliated rocks Point Load Strength Index provides more meaningful information than Schmidt hammer R-values. Geomorphometry is a useful tool to characterize the shape of a coastline and simple indices have the power to discriminate between different types of embayments.