CHAPTER 10: COASTAL PROCESSES, PATTERNS AND LANDFORMS
2. Landforms associated with raised/emergent coastlines (a) Raised beach/Marine terrace
A raised beach or a marine terrace is an emergent coastal landform of deposition. Raised beaches/marine terraces represent an ancient shoreline now exposed above sea level, e.g. near Ballyhillin, Malin Head, County Donegal. They form because of the land rising due to isostacy. During a period of glaciation (ice age) great ice sheets cover the land. Coastal
landforms such as beaches continued to form by the action of constructive waves in sheltered bays unaffected directly by the ice sheet. When the ice melts the huge weight of ice is removed from the land which is then
gradually uplifted out of the sea due to isostacy. The beaches which once marked the ice age sea level are now raised above the present day sea level and form wide terraces. New beaches now form but at a lower level than before.
Fig. 52 A raised beach near Ballyhillin, County Donegal
Raised beach Beach
or marine terrace Present day beach
Sea
Sea bed now exposed due to uplift by isostacy
Fig. 53 Exam Diagram: Formation of a beach during a period of glaciation
Fig. 54 Exam Diagram: Formation of a beach after the ice melts