The morphology of beach cusps on a number of beaches around the South Island, New Zealand is described. Cusp dimensions such as spacing, elevation, amplitude, depth, and spacing variance are interrelated. Cusp dimensions co-vary in regular fashion under different process conditions, such that the cusp form displays a high degree of regularity. Beach cusp amplitude is an exception to this regularity, that appears to be controlled by factors such as grain size and beach slope. Analysis of cusp spacing and elevation dimensions on mixed sand and gravel beaches reveal that cusps having particular spacings form at distinct elevations on the beachface, with the largest spacings occurring at the highest levels on the beachface. The relationship between cusp elevation and spacing provides a technique through which beach cusp spacing can be used to infer mean sea-level. |
