Channel Islands

Introduction

The Channel Islands (British dependencies, and otherwise known as Les Iles Normandes) lie about 130 km south of Portland Bill (Dorset) and to the west and northwest of the Cotentin Peninsula (Normandy, France). They include Jersey about 105 sq. km), Guernsey (62 sq. km), Herm (3 sq. km), Sark (5.5 sq. km), Alderney (8 sq. km) and a number of smaller rocky islets, such as Les Minquiers and the Ecréhou Rocks. They are shown on local topographic maps and British Geological Survey sheets 1 and 2. They consist mainly of Palaeozoic metamorphic and igneous rocks and are generally dominated by plateaux bordered by steep and cliffy coasts and wide rocky shores exposed at low tide. Sand and shingle beaches occupy bays, but erosion has been a problem, and since the eighteenth century there has been extensive construction of sea walls, mainly of dressed granite (Bird 2002). These have held the coastline, but resulted in further beach depletion by wave reflection scour, so that most...