Mega-Geomorphology Defined and Geomorphic Maps - Remote Sensing Application - Completely Remote Sensing, GPS, and GPS Tutorial
Mega-Geomorphology Defined and Geomorphic Maps

The primary thrust of the Tutorial to this point has dwelled on applications - the practical use of remote sensing to oversee conditions or solve problems dealing with the Earth's environments and manmade infrastructures. The emphasis has therefore been on the status of land and water surfaces, and on the overlying atmosphere, insofar as these affect human activities. The payoff from this monitoring is a better understanding of and interaction with (usually changing) events which influence our lives - food production, deforestation, urban expansion, mineral extraction, movement and severity of major storms, flooding, ocean nutrient detection, industrial site selection, to name a few - occurring at both regional and local scales that are readily observable from space.

We don't classify most of the applications, such as those above involving use of remote sensing, under a heading of "Basic Science" studies, although principles of science, such as the physics of electromagnetic radiation, are involved. Purists may argue that information about space "observables," such as determining ozone distribution worldwide, measuring heat flow in the oceans, and observing the biomes and their seasonal variation over the continents, augments the subject matter normally associated with basic science.

Perhaps the best examples of contributions of remote sensing to the fundamentals of science are those associated with exploring planets and astronomy. Similarly, some observations of a geological nature fall more into this "science" niche than into some applications discipline. In this Section, we illustrate that idea by surveying how remote sensing has been a large factor in creating a new subfield in the science of Geology: Global Mega-Geomorphology.

Geomorphology is the study of the shape or configuration of the Earth's (or, by extrapolation, any other planetary body's) solid surface, above and below ocean level, involving the classification of landforms and the processes by which they develop. The term "physiography" relates closely, referring to the description and evolution of land forms. By implication, water bodies, from oceans to small creeks, are participants in geomorphic processes, as major formative agents, even though their shapes tend to be transient and flat in detail.

Until the airplane and then the space age, scientists conducted most geomorphic analysis by on-the ground mapping; generally deriving the input information from topographic (for shape) and geologic (for structure and underlying rock types) maps and by direct field observations and measurements. The observation scales tended to be local or over relatively small areas. Eventually, aerial photographs became a prime tool for mapping and interpreting. The most common format depicted landforms as physiographic maps, using an artist's sketch technique to convey a three-dimensional oblique perspective (exemplified in the top image, below, for part of Utah), or, less often, as geomorphic unit maps

Landforms map of Part of Utah.

A variation of this is the Geomorphic Units map. Here is an example of one made for an area in Scotland:

A selected area within the detailed geomorphic map of the Upper Dee Valley, Aberdeenshire, Scotland.
Key to the above geomorphic map of an area in Scotland.

Geomorphic maps covering large areas–regional in scale–have not been commonplace. In the 1980s, a consortium of geomorphologists produced multi-colored maps of Europe and North Africa. We reproduce below an example of a regional map, showing much of Alaska, made by Soviet scientists.

A first-order geomorphic map of Alaska (symbols identified below)

Key to the above map.

However, in general, geoscientists, especially geographers, did not produce studies and analyses of landforms at large scales, even after Landsat and SPOT products became widely available. Within a few years after launch, these satellite imagers had achieved nearly cloud-free global coverage (about 11,000 individual Landsat frames are needed to cover the continents) of the Earth's land surface (exceptions: the polar regions and some oceanic islands). The ability to combine Landsat or SPOT images into mosaics, such as the one of southern Asia, shown in Section 7, greatly aided the pictorial expression of regional landforms. In effect, we can represent anywhere in the world in picture rather than sketch format, so that we see exact landforms (generally the most obvious features at small scales) of truly regional dimensions.