The History of the Study of Landforms: Volume 1 - Geomorphology Before Davis (Routledge Revivals)

or the Development of Geomorphology

Richard J. Chorley, Antony J. Dunn, Robert P. Beckinsale

• Publisher: Routledge
• Year: 2009
• Print ISBN: 9780415559942
• eBook ISBN: 9781135228637
• Topic: Physical Sciences
• Subtopic: Geography
• Index: Geography

This re-issue, first published in 1964, is the first of a seminal series analysing the development of the study of landforms, from both the geographical and geological point of view, with especial emphasis upon fluvial geomorphology. Volume 1 treats the subject up to the first important statement of the cycle of erosion by W. M. Davis in 1889, and attempts to identify the most significant currents of geomorphic thought, integrating them into the broader contemporary intellectual frameworks with which they were associated. As well as dealing with such key figures as Werner, De Saussure, Hutton, Playfair, Buckland, lyell, Agassiz, Ramsay, Dana, Peschel, Powell, Gilbert and Davis, attention is also given to many less important contributions by American, British and continental workers. A spirited biographical treatment, attractively set off by contemporary portraits, diagrams and sketches, will make this book of great interest to the historian of science, and indeed to the general reader, as well as to the student and scholar in geomorphology, hydrology and any other earth science.

PART ONE

‘Worlds Without End’

CHAPTER ONE
Introduction

To unravel the secrets of nature requires the intuitive wisdom, deductive capacity and experimental ability of generations of scientists. The landmarks of discovery arise from the refined product of their labours. Sometimes research advances by great bounds as a theory is propounded and the many pieces appear momentarily to fall into place. More often it proceeds step by step with one man concentrating on a small fragment and making it his life’s work. The result of his research, and that of others like him, has often to await the entry of the theorist who takes all the parts and builds them into one grand scheme, the very nature of which may point to new lines of research. Study of fluvial and other geomorphic processes has proved no exception to this rule and as the work went forward the task of comprehension assumed increasing proportions.

Through all the ages Man, as he moved within the boundaries of his immediate environment, could not have failed to notice the differences in the surface features or to experience the wilder antics of the elements. On every side of him stood the mighty monuments of nature confounding and prompting reasonings which ranged to the outermost limits of his mental capacity.

Yet throughout the periods of history these varied phenomena have given rise to a series of widely-different explanations. Each man in his turn in exploring nature’s secrets has used his especial skill, together with the acquired ideas and prejudices of his age. From the example of the great scientists it appears that the monuments of nature are best deciphered by a vigorous combination of patient exploration, cautious generalization and constant re-appraisal.

This, we hope, will become apparent in the following chapters where we trace the growth of ideas on the shape and nature of landforms (or geomorphology) with special emphasis on the origin of water-worn landscapes. As in the history of some other branches of scientific knowledge, this tale of evolution, to quote words we shall use so often later, reveals ‘no vestige of a beginning—no prospect of an end’. Yet the account has fascinating peculiarities.

First, from earliest times man’s interest in his physical environment has assured a great and enduring popularity for the study of landscape and of natural forces. Therefore, personal investigations of landscape features have proceeded continuously within historic times.

Second, as this environmental study is mentioned in many parts of the Bible, it became irrevocably linked with theories of the Creation and with theology.

Third, being connected with universal matters, landscape study became peculiarly liable to be dominated by generalizations of universal extent. Such generalizations often preceded and took control of detailed deductions. It would be hard to imagine a more stultifying situation for a youthful ‘science’.

Fourth, it was inevitable that the steady progress of practical work or fieldobservations would lead to the overthrow of many ill-founded universal generalizations, which would then be replaced by universal laws based on more scientific principles.

Fifth, even to this day, in spite of countless spasmodic and short-term observations, there has been a marked absence of continuous measurements or long-term recordings of landscape processes, except perhaps on floods, rainfall, earthquakes and violent vulcanism. Thus geomorphology remains a pseudo-science with a largely unscientific tradition. No doubt a century hence it could, if given today a proper basis of physics and physical chemistry, be called an earth science.

The story we have to tell begins with the interest of man in the work of nature, more particularly through the agency of water, and in his inheritance of the tradition of a great flood, a tradition derived no doubt from human experience in the last Ice Age and the pluvial epoch following it. The present volume ends with the global generalizations of William Morris Davis, who throwing caution to the winds and ignoring many contemporary scientific observations, published a most attractive theory of landscape evolution. In venturing to suggest that Davis took only a partial view, we maintain the ancient geomorphological tradition of opposing inadequate generalizations.

It should be noticed that all generalizations on landscape evolution fail largely because of relative lack of knowledge of erosional processes and because of ignorance of the interaction between the earth’s crust and the earth’s interior. Ignorance of vulcanism and earth movements proved the weak links in the ideas of the Wernerians, Huttonians, and Davisians alike. Modern geophysicists are only just beginning to delve into the problem. These twentieth-century aspects of the study of landscape evolution we intend to treat in further volumes. Here we end with Davis not only because he, by his magical generalizations, lulled the geomorphological world into a temporary slumber, but also because he was a great figure, who occupied a worthy place in a long line of fascinating personalities stretching back to Hutton and beyond.

CHAPTER TWO
Early Ideas on Erosion and Rock Strata

INTRODUCTION

Faced by the daily testimony and record of the massive operations of nature’s agents and the colossal proportions of their structures, it is not surprising that man’s first explanations of the World were visionary and in the form of fables. To the Christian peoples of the west the story of creation in the Book of Genesis is the best-known example. The eastern peoples had their own versions (Suess, 1904, I). All the stories taught that the world was created by supernatural persons or forces in a relatively short space of time and that it had since retained, to a substantial extent, its original form. This is not to say that the ancients did not recognize the existence of recurrent events like floods and tempests—the Bible is full of such topics—but that these occurrences were regarded as being only of local or temporary significance. During the Middle Ages, when perhaps the Church had its strongest hold over the laity and the advancement of learning, the notion of a single act of creation became rigidly enforced on the principle that it was a religious truth.

Consequently, in the early history of landscape studies we are faced with a strange dichotomy: the abundance of observers who recognized that erosive forces were actively fashioning the earth’s surface; and the superabundance of people who considered that the earth’s features were created in the six days of the Creation. These ideas might well have remained separate but for the great interest taken in fossils. Indeed the sea-shell on the mountain-top has been of supreme importance in the history of landscape study and may even have been of more significance than the countless early observations on the obvious erosive force of rivers and waves. It happens, however, as we have already hinted-, that ideas on erosion need not be applied universally and need not offend cosmogonists whereas ideas on sea-shells in mountain rocks involve the Creation and world floods and discussion upon them soon opens the flood-gates of theology. In this chapter we shall attempt to show briefly how some writers restricted their observations to erosion and others to fossils and how any who tried to combine speculations on both were eventually forced to reconcile landscape evolution with theological cosmogony.

ANCIENT EROSIONISTS

Among the Greeks one of the chief geological figures is Aristotle (384–322 B.C.), who theorized that the cold temperature of mountains condensed the atmospheric moisture and gave rise to the origin of streams. From the presence of rock strata he surmised a regular series of mutations between dry land and sea, and between tropical and polar temperatures; and here he anticipated Hutton. As a Greek, Aristotle was not hampered by religious inhibitions and his field of speculation was not blurred by a priori reasonings. However, unfortunately, he did not find the uncertainties of the physical processes of nature a fruitful source for logical hypotheses, so dear to the classical Greeks, and he pursued his observations no further. This neglect by the Greeks of the natural sciences contributed notably to the retardation of the growth of those studies in Britain where well into the nineteenth century many establishments for education were mainly concerned with the teaching of classical knowledge.

In fact, none of the ancient classical authors progressed in the natural sciences as far as the Arab philosopher and physician, Avicenna (A.D. 979–1037), who seemed to have glimpsed the vision of a continuous succession of landscape processes and pointed out that the natural topography could result from the action of running water.

THE FIRST MODERN EROSIONISTS AND PALAEONTOLOGISTS

The later medieval period was marked by a great interest in earth features as contemporary paintings reveal in their striking landscape backgrounds. Several authors now showed a remarkable advance in the study of landscape formation and their writings began to combine ideas on erosion and on fossils into universal generalizations of a cosmogonical kind.

It is in a sense unfortunate that we have to begin our account with Leonardo da Vinci (1452–1519) whose work was of such a quality that it might well have represented the culminating thoughts of a long line of illustrious thinkers. As it was, in landscape studies Leonardo seems to have outstripped in intelligence his predecessors and immediate successors alike. It would be hard not to say that he grasped firmly the ideas both of local erosion and of world-wide landscape evolution.

The following quotation demonstrates the quality, width and stupendous foresight of his observations on the evolution of topography.

I perceive that the surface of the Earth was from of old entirely filled up and covered over in its level plains by the salt waters, and that the mountains, the bones of the earth with their wide bases, penetrated and towered up amid the air, covered over and clad with much high-lying soil. Subsequently, the incessant rains have caused the rivers to increase, and by repeated washing, have stripped bare part of the lofty summits of these mountains, leaving the site of the earth so that the rock finds itself exposed to the air, and the earth has departed from these places. And the earth from off the slopes and the lofty summits of the mountains has already descended to their bases, and has raised the floors of the seas which encircle these bases, and caused the plain to be uncovered, and in some parts has driven away the seas from there over a great distance. (Translated by McCurdy, 1906, pp. 94–95)

In the following vivid passages he refutes the possibility that the existing fossil remains found on mountain and plain could have been the product of the biblical forty days and forty nights of rain and instead he asserts that the presence of fossil beds at high altitudes is proof of changes in level between the land and the sea:

If you should say that the shells which are visible at the present time within the borders of Italy, far away from the sea and at great heights, are due to the flood having deposited them there, I reply that granting this flood to have risen seven cubits above the highest mountain, as he has written who measured it, these shells which always inhabit near the shores of the sea ought to be found lying on the mountain sides, and not at so short a distance above their bases, and all at the same level, layer upon layer.

Should you say that the nature of these shells is to keep near the edge of the sea, and that as the sea rose in height the shells left their former place and followed the rising waters up to their highest level:—to this I reply that the cockle is a creature incapable of more rapid movement than the snail out of water, or is even somewhat slower, since it does not swim, but makes a furrow in the sand, and, supporting itself by means of the sides of this furrow it will travel between three or four braccia in a day; and therefore with such a motion as this it could not have travelled from the Adriatic sea as far as Monferrato in Lombardy, a distance of two hundred and fifty miles in forty days—as he has said who kept a record of that time.

And if you say that the waves carried them there—they could not move by reason of their weight except upon their base. And if you do not grant me this, at any rate allow that they must have remained on the tops of the highest mountains, and in the lakes which are shut in among the mountains…

If you should say that the shells were empty and dead when carried by the waves, I reply that where the dead ones went the living were not far distant, and in these mountains are found all living ones, for they are known by the shells being in pairs and by their being in a row without any dead, and a little higher up is the place where all the dead with their shells separated have been cast up by the waves, near where the rivers plunged in mighty chasm into the sea. (Translated by McCurdy, 1906, pp. 106–7)

Where the valleys have never been covered by the salt waters of the sea, there the shells are never found. (Translated by McCurdy, 1906, p. 109)

The water wears away the mountains and fills up the valleys, and if it had the power, it would reduce the earth to a perfect sphere. (Translated by McCurdy, 1906, p. 101)

The shells of oysters and other similar creatures which are born in the mud of the sea, testify to us of the change in the earth round the centre of our elements. This is proved as follows:—the mighty rivers always flow turbid because of the earth stirred up in them through the friction of their waters upon their bed and against the banks; and this process of destruction uncovers the tops of the ridges formed by the layers of these shells, which are embedded in the mud of the sea where they were born when the salt waters covered them. And these same ridges were from time to time covered over by varying thickn...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Preface
• PART ONE: ‘WORLDS WITHOUT END’
• PART TWO: THE AGE OF LYELL: 1820–1845
• PART THREE: MARINE VERSUS SUBAERIAL EROSIONISTS: 1846–1875
• PART FOUR: THE WESTERN EXPLORATIONS