As has been repeatedly mentioned in the foregoing paragraphs, the details of coastal topography often show no obvious relations to the geological structure of the rocks. On a grand scale, however, the position and. trend of coast-lines are controlled by tectonic features, and frequently the details are similarly determined. Many coasts are due to great systems of faults, which may, as in the Atlantic shores of Europe, intersect the prevailing lines of strike, or may run approximately parallel with those lines, as in eastern Asia, where a series of tilted fault-blocks form the plains, the coast-lines, and the lines of fringing islands. Other coasts are coincident with long lines of folding, as is illustrated by the entire west coast of North and South America, the foreland of the great mountain chains being more or less completely submerged. The Dalmatian coast on the east side of the Adriatic is a half-submerged belt of folding and the coast-line obliquely truncates the strike. Fjord, rias and calas coasts may occur in association with any type of structure; they are determined by the dominant class of subaerial denuding agents.