Mass wasting and subaerial weathering in guyot formation: the Hawaiian and Canary Ridges as examples

By using a combination of bathymetry and topography in the computerized GRASS 3D package, guyot evolution has been determined on the fast-moving Pacific plate for the subaerial, low sloped Hawaiian Island chain. On the slow-moving African plate, the timing of guyot formation has been determined for the subaerial, steeper sloped Canary Islands chain. In the Hawaiian chain, the Niihau Island platform was already essentially formed, although there is a platform at the 180 m elevation on Kauai Island if the remaining peaks are discounted. By Fuerteventura Island in the Canary chain the seamount/island has already been flattened. Both of these platforms are far above the influence of wave cutting. The causal agent of flattening is primarily mass wasting by landsliding, caused in part by earthquake activity on the moving plates. This disproves the subsidence and wavecut theory of guyot formational processes in that the guyot is already formed before it subsides. The islands lie in the tropical coral zone, yet coral formation has little effect on the flattening process. This may be because the turbidity from slumps kills the coral. This exercise also gives a time limit for the reduction of pristine volcanic slopes to the typical guyot surface, that time being between one and four million years. It is apparent that wave cutting merely polishes the stone, applying the finishing patina.