"Abnormal" Shore Platforms

Abstract

Conditions in New Zealand are especially favorable to the study of shoreline forms, and, probably for this reason, New Zealand geologists are impressed with the frequency with which subhorizontal benches are developed near high-water level on rocky, retrograded coasts, and, whatever individual beliefs may be held as to their origin, discussions have made it obvious that local geologists are strongly of the opinion that such benches are a far commoner feature than the literature would lead one to expect. The present paper aims at briefly discussing shore platforms which make a distinct departure from the profile which has been described as the "normal shore profile," or the "profile of equilibrium," and for this reason only has the term "abnormal" been applied to them in the title of this paper. The writer firmly believes that such platforms are in no respect truly abnormal, but that characteristically they are expectable, and therefore the normal products of shoreline erosion, and is assured by correspondence that his is no isolated belief. Ten years ago the writer published a brief paper on certain rock platforms which are a prominent and characteristic feature of shoreline topography in many harbors of North Auckland, and of which an outstanding example is afforded by the well-known "Old Hat" near Russell in the Bay of Islands, New Zealand.' As with most other North Auckland harbors, the Bay of Islands has been formed by the submergence of a maturely sculptured land-mass, and the Old Hat, which is illustrated in Figure i, represents an emergent