Granite Coasts

Although no estimate of the aggregate length of granite rock coasts around the world is available, they surely make up quite a significant proportion of the total, especially around the Fennoscandian and Canadian Shield (Bird and Schwartz, 1985). However, in contrast to the vast amount of literature about inland granite landforms, granite coastal scenery has attracted significantly less attention, in spite of the fact that some of the most spectacular coastal landscapes are supported by granite (Plate 6.1). Detailed studies of granite coastal geomorphology are surprisingly few, although the structural adjustment of the coastline in plan at the regional scale is a recurrent observation (Bird and Schwartz, 1985). One probable reason for this discrepancy between the length of granite coasts, their scenic values, and scientific knowledge are the low rates of geomorphic change expected along them. Therefore they are poor candidates for any process-oriented studies, which dominate contemporary coastal geomorphology. It is probably because of this scarcity of information that contrasting opinions have been expressed about the specifics of granite coasts. Whereas Twidale (1982: 2) asserts that: ‘In coastal contexts, too, the gross assemblage of forms is due to the processes operating there and not to properties peculiar to granites. . . . Orthogonal fracture sets also find marked expression but, with few exceptions, granite coasts are much the same as most others’; Trenhaile (1987: 173) goes on to say: ‘Igneous coasts are usually quite different from other rock coasts’. On the one hand, many granite coasts consist of an all-too-familiar assemblage of cliffs, coves, joint-aligned inlets, stacks, and sea arches. From this point of view, no components of coastal morphology are likely to be demonstrated to be unique to granite. But this is also true for granite landforms in general, as was indicated in the introduction to this book. On the other hand, there seems to be enough observational material to claim that certain granite coastal landforms have developed specific characteristics, different from those supported by other rocks, as well as that there exist certain very specific sections of granite coasts which hardly have parallels in other lithologies.