Geol 33 Environmental Geomorphology
J Bret Bennington
Introduction - What is Environmental Geomorphology?
First, let's try to define Geomorphology. Basically, geomorphology is the study of the present surface of the earth - how it developed to become what it is and the processes that shaped it. This is a branch of geology that has roots older than any other. For example, Herodotus (485?-425 B.C.) and Aristotle (384-322 B.C.) both considered explanations for such observations as the growth of the Nile, the elevation of marine rock above sea level, the subsidence of land beneath the sea, and the erosion of river valleys. People have always been interested in the topographic features of the Earth's surface - after all it is what we live on and interact with on a daily basis.
In many ways, Geomorphology is also very much the study of the Quaternary Period of geologic time. The Quaternary encompasses the Pleistocene and the Holocene (the last 1.6 million years of Earth history) and includes the present ice age, in which we have the good fortune to be living during one of the periodic interglacial warming episodes. Ice ages have had a profound effect on the modern topography, particularly in northern latitudes and in mountainous regions that have recently hosted glaciers. Indeed, to understand the Holocene requires that we understand what happened in the Pleistocene because the climates and processes that produced much of our present landscape are no longer operating there.
This is not to say that the pre-Pleistocene is not important. As we will see, geologic events that occurred hundreds of millions and even billions of years ago still exert their control on the landscape.
Geomorphology is also one of those sciences that seems to inhabit an intersection between many others. To understand landscapes, landforms, and their evolution through time requires knowledge of all of the things that impact on these features and processes - climate, mineralogy, chemistry, tectonics, sedimentology, and ecology, just to name a few of the more important ones.
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The Environmental Approach
But what does geomorphology have to do with environmental science? One could say that environmental geomorphology is applied geomorphology. In other words, using an understanding of landforms and surface processes to better coexist with them.
Notice that I did not say control. "Nature to be Commanded" is the hubristic title of a USGS publication on engineering geomorphology from the 1960's. We are beginning to realize that much of the 20th century will be remembered as a time when we vastly overestimated both our ability to control nature and the benefits of trying to do so. The last two decades have seen unprecidented levels of expense generated by natural disasters and environmental disruption exacerbated by our attempts to control geomorphic processes.
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The Environmental Ethic
Environmental Geoscience as practiced today has matured from a single-minded pursuit of resources and solutions to engineering problems (what might be better defined as Îeconomic geologyâ) into an essential component of a scientifically driven environmental ethic.
The Environmental Ethic was first articulated by Aldo Leopold in an essay called ÎThe Land Ethicâ published in 1949 in his famous ÎSand County Almanacâ. What is the land ethic? Leopold explains is thus:
"All ethics so far evolved rest upon a single premise: that the individual is a member of a community of interdependent parts. His instincts prompt him to compete for his place in that community, but his ethics prompt him also to co-operate (perhaps in order that there may be a place to compete for).
The land ethic simply enlarges the boundaries of the community to include soils, waters, plants and animals, or collectively: the land.
This sounds simple: do we not already sing our love for an obligation to the land of the free and the home of the brave? Yes, but just what and whom do we love? Certainly not the soil, which we are sending helter-skelter downriver. Certainly not the waters, which we assume have no function except to turn turbines, float barges, and carry off sewage. Certainly not the plants, of which we exterminate whole communities without batting an eye. Certainly not the animals, of which we have already extirpated many of the largest and most beautiful species. A land ethic of course cannot prevent the alteration, management, and use of these Îresourcesâ, but it does affirm their right to continued existence, and, at least in spots, their continued existence in a natural state.
In short, a land ethic changes the role of Homo sapiens from conqueror of the land-community to plain member and citizen of it."
A major point Leopold (and other famous conservationist writers) tried to make was that the environment in its natural state had values beyond those of simple economics. Many environmentalist would argue (as Leopold did) that animals, plants, and the environments they inhabit have an intrinsic right to exist and that humans should respect that right.
It is not clear that anything besides humans can have Îrightsâ (an interesting and complicated philosophical question). However, we can certainly agree that natural environments have asthetic value that is difficult to put a price on. Anyone who has wandered through the woods on a cool autumn day or hiked through a meadow in late spring appreciates this.
But just as important, if not more so, ecology, biology, and geology have shown that natural environments have many functional properties that are directly beneficial to humans. Forest ecosystems consume CO2, produce oxygen, and ameliorate climate. Ocean ecosystems do many of the same and produce the fish and other seafood that are major protein sources for many of the world's societies. Estuaries trap silt and detoxify water pollution in rivers. Forests also stabilize soil and moderate runoff from rainfall. Soils, in turn, provide the basis for agriculture and sustain forests.
Also, failure to understand and to respect the functioning of natural geological systems usually results in eventual property destruction and loss of life. Examples include:
A recurring theme through history is how humankindâs control and overutilization of the land and its resources for short term economic gain almost always results in the long term destruction of the resource being exploited at a cost to society that far outweighs the initial monetary gain.
In short, the environmental ethic can be summarized as:
This environmental ethic is nothing more or less than enlightened self interest. We are children of the Earth and its natural systems, the result of millions of years of ecology and evolution. Our technology , our culture, and our biology depend on the funtionality and products of those systems. We change them, destroy them, or ignore them at our own great risk.
Traditionally, environmental studies have been associated with biology, ecology, and biochemical cycles. This overlooks the important physical components of environments - the geology and physiography on which they exist - which have generally been referred to engineers for remediation (fix it so it does what we want it to do) rather than studied to understand how they function.
Thus, in this class we will attempt to develop three approaches to geomorphology.