2.1: Introduction

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Judith Bosboom & Marcel J.F. Stive
Delft University of Technology via TU Delft Open

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Present-day coasts show the imprint of both present-day processes and past processes. Coastal morphology is thus partly inherited from the past. Section 2.2 introduces the long timescales of geological processes and sea-level changes and the concept of inheritance.

In Ch. 1 it was mentioned that the characterisation of a coastal system is dependent on the scale that we consider. The broadest (or first order) features of the coast cover large geographical distances (thousands of kilometres) and are linked to the long-term geological process of plate tectonics. Plate tectonic theory and the consequences for coastal systems are discussed in Sect. 2.3.

Many of the geomorphologic features shaped or deposited during the Quaternary – consisting of the Pleistocene and Holocene – are still clearly recognisable at present. These coastal features are superimposed on the pre-existing geology that is controlled by plate tectonics. The Pleistocene legacy of rocky coasts is briefly treated in Sect. 2.4, whereas Sect. 2.5 discusses the effect of Holocene sea-level changes in combination with availability (supply or loss) of sediment.

Section 2.6 deals with large-scale variations in nature and abundance of coastal material. This will be shown to be coupled to geological controls as tectonic plate setting and glacial action, and to climate. The relevant climatic effects, such as global wave height distribution and discharge of the world’s largest rivers are therefore also briefly treated in Sect. 2.6. More specific information on global variation of wind, wave and tidal characteristics and effects on coastal developments are treated in Ch. 4.

On regional (tens to hundreds of kilometres) and local scales (only a few kilometres) second and third order features become noticeable. In order to describe these regional and local features, a process-based approach will be introduced in Sect. 2.7, which will be followed in the remainder of these lecture notes.