Editorial
Submarine geomorphology: new views on an ‘unseen’ landscape

Abstract

Geomorphology, one of the oldest disciplines in the geosciences, is undergoing a rebirth in the submarine environment. 2D (i.e. gridded) high-resolution bathymetry data offers exciting views of ever more of this hidden landscape, allowing a much improved understanding of both the solid Earth and Earth surface processes that shape the seabed. Such geomorphology is particularly powerful when convolved with geophysical techniques that image the sub-seafloor to form 3D studies.This journal issue promotes a vision where submarine geomorphology i) unites processes typically studied in sub-aerial geomorphology (e.g. landsliding & channel erosion) and marine geophysics (e.g. volcanism, tectonics & geodynamics) ii) strives to progress beyond purely qualitative methods and to employ quantitative approaches in analyses and iii) integrates bathymetry with other surface or subsurface data to enhance the analysis. The aim in bringing together work on the various causes and consequences of the underwater landscape is to endorse interaction and knowledge transfer between disciplines and study areas.This editorial highlights the links between submarine geomorphology, geophysics, Earth surface processes and bathymetry. Questions from the issue reviewed here include: How does the Earth melt? How does seafloor morphology affect the size of subduction earthquakes? What is the interconnection between submarine mass-wasting and tectonic environment? Submarine Geomorphology & Geophysics, a Historical PerspectivePractically, it is not possible for humans to directly observe the vast majority of the seafloor. This is in direct contrast to the sub-aerial landscape. Contrast, for example, a pilot looking down from an aircraft and a sailor looking over the side of his craft. Even in the best conditions seawater is opaque to visible light beyond a few hundred metres penetration. Because it cannot be viewed, or indeed easily walked around upon, the seafloor can be thought of as an 'unseen' landscape that is in some ways less accessible to us than the surface of Mars. Electronic geophysical equipment is necessary to measure the deep ocean at any level beyond the most cursory and crude. Developments in submarine geomorphology have therefore been intrinsically linked to developments in geophysics. This is simply not true for sub-aerial geomorphology where less sophisticated equipment (e.g. a plane table) can produce accurate data, and this contrast probably explains the differential and disparate development of geomorphology on land and underwater.Long before geophysics, however, water depth was critical information for the purposes of navigation, so 'soundings' have been taken, firstly using a long pole. From the 1870s hemp rope with a lead weight attached was used by HMS Challenger and USS Tuscarora, continued with the United States Fish Commission steamer Albatross from 1888 until the early 20 th century when a wire cable method began to be used. Soundings taken by these methods were neither quick nor cheap to obtain, so only a few th...