The Man and the Hill

GEOLOGICAL SURVEY 

CIRCULAR 460-A
Part A

The Man and the Hill

By Luna B. Leopold

CONSERVATION NETWORKS

GEOLOGICAL SURVEY CIRCULAR 460-A

This volume complete in three parts

Washington 7962
United States Department of the Interior

STEWART L. UDALL, Secretary

Geological Survey

William T. Pecora, Director

First printing 1962 

Second printing 1967

Free on application to the U.S. Geological Survey, Washington, D.C. 20242
GEOLOGICAL SURVEY CIRCULAR 460-A 

CONSERVATION NETWORKS

PART A

The Man and the Hill

By Luna B. Leopold

Opening address to the Symposium on Climatic Change, 

United Nations Educational, Scientific and Cultural Organization and World Meteorological Organization, Rome, October 

1961.

He was sitting on a large slab of rock. As 

he looked at the cloud of dust hanging hazily 

on the horizon, the piece of antler and the 

block of flint he held in his hand hung as if 

they were suspended from their previous 

rapid motion. The man gazed intently across 

the swaying grass which rose in wave-like 

billows across the distant hills. What was 

that dust a herd of buffalo, a band of hunters, 

or were coyotes chasing the antelope again? 

After watching for a while he started again to 

chip the flint with a rapid twisting motion of 

the bone in his right hand. The little chips of 

flint fell in the grass before him.

It is the same hill but the scene has changed. 

Seated on the same rock, holding the reins of 

a saddle horse, a man dressed in buckskin 

took the fur cap off his head and wiped his 

brow. He was looking intently across a brown 

and desolate landscape at a cloud of dust on 

the far horizon. Was it the hostile tribe of 

Indians? It could be buffalo. Nervously he 

kicked at the ground with the deerhide moc - 

casin, pushing the flint chips out of the way. 

He wiped the dust from his long rifle. What 

a terrible place no water, practically no 

grass, everything bare and brown.

Now at sunset, slanting across the hills 

green with springtime, a cowman sits on a 

big rock, pushes his sombrero back on his 

head, and looks across the valley at a large 

but quiet herd of stock, moving slowly as 

each steer walks from one lush patch of grass 

to another, nibbling. Suddenly he stood up. 

Far on the horizon some dark objects were 

moving. Is it the sheepmen? Could it be the 

stage coach from Baggs to the Sweetwater 

Crossing?

Same hill a gray truck was grinding slowly 

toward the summit. It pulled up near a small 

fenced enclosure where there were some instruments painted a bright silver color. A 

man stepped out of the truck and turned to 

his younger companion, "You've never found 

an arrowhead? Maybe you have never thought 

about it correctly. If you want to find where 

an Indian camped long ago, put yourself in his 

place. Where would he sit to chip flint? He 

would take some high hill above a grassy 

valley where the breeze would cool him and 

where he could look across the country, 

watching for game or for enemies. If I were 

an Indian, that's what I would do. You change 

the chart of the rain gage and I am going to 

walk up to the place where I think he might 

have sat." He walked over to the crest of the 

hill and, near a large slab of sandstone, 

started to pick up pieces of flint.

This is an oft-repeated story. A given hill 

is repeatedly visited, used, loved or hated, 

protected or marred, by successive generations of men. All these men had characteristics in common. They had a job to do, a 

livelihood to make; they had their own plans, 

their own fears, but they were in one way or 

another connected with the land.

But the land itself was not static it changed 

in time from season to season, year to year, 

and century to century. The soil and chips of 

rock, beaten by the elements, the hooves of 

beasts, and the feet of men, move gradually 

but inexorably down the slope. Each suc- 

 ceeding generation of men left some mark on 

the hill. That mark is usually erased with 

time but under certain circumstances the 

sequence of events can be reconstructed with 

considerable assurance. And I think it would 

be true to say that the hill also left some 

mark on the men. This mark may be only a 

passing memory, but many men have grown
up on many hills, and the hills have, at least 

to some extent, conditioned man's attitude and 

his view of the environment in which he lives.

Now we are engaged in a great struggle 

with those hills, more intense than at any 

other period in the earth's history. The expanding population requires ever-increasing 

supplies of the natural resources which are 

found on or in these hills the grass, the soil, 

the water, the minerals, and the timber. By 

extracting these, man's mark on the environment becomes ever deeper, his effects ever 

more indelible. But his ability to obtain or to 

manage these resources depends on an ever 

more sophisticated understanding of the characteristics of the resources, their mode of 

occurrence, and their response to management. Particularly in the renewable resources, the response to management is often 

not clearly separable from the response to 

slow and subtle changes in the natural environment. The most pervasive and probably 

the most important of these slow and subtle 

natural changes result directly or indirectly 

from variations in climate. Over a shorter 

or longer period of time the variations in 

climate affect the type and characteristics of 

the soil profile. Its ability to take in and store 

moisture and the supply of water is simultaneously governed by the same climatic factors. In response to the changes in moisture 

and conditions of soil, the vegetative association also tends to change. New combinations 

of species, having different types of interaction with soil and moisture, move in and displace the previous species. The insects, the 

animals, the bacteria are similarly influenced 

by this interdependent complex, and they 

change also.

With variations in climate come new conditions of equilibrium. Particularly in arid 

climates is there a sensitive balance between 

the erosive effects of water and gravity and 

the ability of the vegetation to hold the soil 

and mitigate the erosive effects of running 

water. It is an axiom in ecology that the climatic factors, soil, and the biota interact in 

such a way as to promote a quasi-equilibrium, 

notwithstanding the long-term geologic effects 

of gradual degradation of the continents by 

solution and by the processes of erosion.

Interestingly, many of the effects of man's 

action on this complex and on the conditions 

of quasi-equilibriumare similar to the effects 

of thelong-term variations in climate. Man's

utilization of the vegetation for grazing, for 

lumber, or for agriculture tends to alter the 

relation between hill slopes, vegetation, and 

water. An overgrazed range is characterized 

by the decrease in volume growth, by the 

gradual replacement of some species by 

others, particularly the replacement of perennials by annuals, a general simplification 

of the biota, and a. short-cutting of food chains. 

These same reactions of the landscape are 

those which would result from a change toward greater aridity. The decrease of volume growth and density of grasses under 

conditions of excessive grazing results in a 

deterioration of soil tilth, a reduction in infiltration capacity, increased susceptibility 

to erosion,and usually increased erosive potential of the available surface runoff. A 

change in climate through its effect on vegetation, and thus on rainfall-runoff relationships, can be remarkably similar to the effects of man's use.

We have produced a machine, the bulldozer, 

with remarkable efficiency for doing geologic 

work. But we have only begun to study how 

resources can be managed for optimum production and for social advancement. In the 

field of water development and in the field of 

agricultural production, full development is 

in sight at least in some drainage basins, 

even within the present generation. Optimum 

management is going to depend greatly on an 

understanding of the natural relations which 

produce the qua si-equilibrium that characterized the landscape before the advent of man. 

A principal object of present-day research in 

the field of natural resources is to unravel 

these complexities that govern the natural 

quasi -equilibrium.

It therefore becomes a matter of practical 

concern, as well as a matter of intellectual 

interest,that the specific causes of given observed effects be identified and that the chain 

of events the linkage of interrelated factors 

be known in far more detail than is possible 

at present. Specifically, the ecologist, the 

geologist, the botanist, the zoologist, the sociologist, and a host of others find themselves 

unable to link cause and effect because they 

cannot dissociate the direct and indirect effects of man's use from the similar effects 

which are brought about by the natural variations in climatic factors.

If, then, it seems abstruse or unimportant 

that we gather here to discuss the nature, the
causes, and the tools by which we study climatic variation, let us disabuse the mind of 

such a casual observer of this misconception. 

On the contrary, in the field of water resources the field I know best management 

isbecoming increasingly dependent on an improved basic understanding of the interrelations between the atmosphere, the biota, and 

the land as they affect the hydrologic cycle. 

To gain a workable understanding of these 

interrelations it is imperative that we know 

more than we do at present about the nature 

of, and the effects emanating from, climatic 

changes.

This problem is of greater concern in the 

arid areas of the earth than it is in the more 

humid ones. First, the arid areas are characterized by an inherent variability, particularly in climatic factors. This variability is 

reflected in the biota. Secondly, in an arid 

climate the climatic controls are somewhat 

more direct than they are in areas where 

water is not a limiting factor. The responses, 

even to relatively minor climatic variations, 

are more specific and more prompt.

A subject of the highest priority in aridzone research should be the mechanics and 

processes in the hydrologic cycle wherein the 

natural changes resulting from climatic variation are confounded and confused with the 

changes caused by man's activities.

Many of us have been associated over the 

past several years with a concerted effort to 

focus attention on the problems of the arid 

zones. We have organized and attended meetings and symposia, we have formed committees, we have instigated research laboratories 

and student training programs a myriad of 

activities. Important as are these activities 

in stimulating an interest and knowledge of 

the arid zone, they often deal with relatively 

distant and abstruse aspects of the total problem. Further, few of these are of such nature 

that they involve many people in many countries. There are other immediate, practical, 

and inexpensive ways of achieving some of 

our objectives, particularly the acquisition of 

new and vitally needed information. Such information has educational value in promoting 

a greater public understanding of the nature 

of arid-zone problems. One such specific is 

the following.

Vitally needed now is an international system of observations on small watersheds of

the principal hydrologic and landscape factors. Field observations of the same kind in 

many places would improve our under standing 

of the hydrologic and the biologic aspects of 

the interrelation between the man and thehill, 

I hereby call, therefore, for the establishment 

of an international network of observation 

points to collect data on some of the basic 

parameters governing the relation between 

man and the landscape in arid zones. The 

network of observation areas I visualize 

might consist of the following.

A small watershed would be chosen, the 

size of which might be from one to ten square 

miles. It would be chosen to represent a 

typical area in the general region that is, 

typical in its general geology, vegetation, 

slopes, topography, and land use. At the mouth 

of the drainage basin some very simple observations would be made intermittently. The 

major flows in the stream channel would be 

observed by means of an extremely simple 

instrument devised in our country which we 

call the crest stage gage. This is merely a 

perforated pipe standing near the stream 

channel within which is contained a wooden 

measuring stick and at the bottom of which is 

dumped some burnt cork. When the water 

rises in the channel the cork floats up and 

clings as a high-water mark to the stick inside the pipe. At some later time the observer conies to the crest stage gage, pulls 

the stick out of the pipe, observes the position 

of the cork which is the high-water mark of 

the most recent flow, and records its vertical 

position.

Another observation which can be made 

very easily is the cross-sectional shape of 

the channel at the point of observation. A 

cross section can be surveyed, tying it at each 

end to permanent monuments. These monuments or markers might be as simple as a 

cross chipped in local rock at each end of the 

channel. Where rock is not available, an iron 

pipe can be driven into the ground, which will 

not be disturbed by ordinary activities of man 

or beast. Such cross sections could be resurveyed seasonally, or even once a year. 

The changing cross section over a period of 

years would give a quantitative idea of whether 

the channel is aggrading or degrading.

As many of you probably know, in most field 

situations it is practically impossible even 

for the expert to look at a stream channel and 

tell whether the channel is presently in a
period of gradual aggradation or gradual 

degradation.

Obviously, in the measurement locality 

there should be a long-term storage rain 

gage. These instruments are now available 

cheaply and have been shown to give good results. A gage buried in the ground and containing a few drops of oil or other material 

to reduce evaporation can give a very usable 

record of the seasonal precipitation. Rain 

gages do require some sort of a fence or 

barricade to protect them from passing stock, 

but such protection can be furnished at very 

low cost. If a small enclosure is built to hold 

a rain gage there is then the possibility of 

having a trap for obtaining samples of windblown pollen and windblown dust. At the same 

place one may collect samples of rain to 

measure its content of dissolved chemical 

salts.

Apart from these measurements which are 

made seasonally or annually at the mouth of 

the watershed, each watershed should have a 

cursory description of its soil, geology, topography, and vegetation. Quadrants, transects, or some other simple means of describing the vegetation are necessary in order 

to give quantitative estimates of the gradual 

change, if any, in plant growth or species 

distribution.

As an initial step in our part of the suggested network, we in the United States are 

proposing a series of small watersheds be 

chosen along a line or transect stretching in 

an east-west direction between the major 

mountain masses in the North American Continent. Later we hope also to have a similar 

series of watersheds in a north-south line 

through the central part of the United States 

where the topography is relatively flat. The 

north-south transect, then, would give a representation of the effect of latitude uninfluenced by major differences in topography.

One might ask why it is necessary to suggest that this hydrologic network of bench 

mark areas be formulated on an international 

basis. To me the answer seems quite clear. 

Not all the possible conditions of vegetation, 

soils, climate, and use are represented even 

in a very large country. The first purpose of 

having such an international network is, 

therefore, to get a sampling of diverse types 

of landscape in different parts of the world. 

The second reason why this program should

be of an international nature is that many of 

the climatic and use factors have a distribution dependent partly on continentality, on relation to major bodies of water, and on other 

characteristics of aspect and position. To 

obtain such a range in conditions, the observations should be on various continents.

What I suggest is practical in terms of the 

types of instruments and observations which 

are required. Standardization, even of very 

simple observations, can give a large amount 

of very useful information, and has the advantage of offering the possibility for immediate installation. Observations that require 

very specialized equipment, highly trained 

manpower, or considerable cash outlay are 

difficult to initiate. The suggestion made 

here, on the contrary, has actually beentested 

in the field; the instruments are of the simplest sort; the time schedule for observations 

is not critical; and the long-term results of 

such observations have already proven their 

great usefulness.

Allow me to propose that this network of 

simple observational areas be called the 

Vigil Network. A vigil is a watch, an observation 

over time, if you will. It comes from the 

Latin, vigilo, to watch. We will watch the 

changes that occur with time in the vegetation, the channels, the biota, and the landscape. If one considers the name Vigil is not 

specific enough, let it abbreviate a more formal designation: Veglia Idrologica,Globale e 

Internazionale di Luoghi d' Osservazione 

Hydrologic Vigil at Comprehensive International Sites.

In proposing, then, an international network 

of landscape observations on small drainage 

basins, I hope we will begin a trend toward 

true international cooperation even of relatively simple nature, within the practical 

limitations of manpower and money. Too long 

have we devoted most of our major attention 

to the establishment of costly and complicated 

programs which take years to initiate. What 

I am suggesting is within the reach of even 

the smallest countries; the amount of initial 

effort for installation is very small; the possibility of having uniform methods adopted 

by various countries is good; and the program can be started by any scientist regardless of his particular background or training.

I hope that the present symposium will 

bring out in the papers examples of the
principle which I have stated that the interaction of the effects of man and the effects of 

climatic change can be separated only by research. I hope further that there might be 

some response to this suggestion for the installation of an international network of observation areas. If I seem to see interest in 

this proposal, I wish to transmit to Prof. 

Tison of the International Association of 

Scientific Hydrology and to the World Mete - 

orological Organization suggested specifications for the choice of the drainage basins in 

such a network, a description of the type, 

operation, and availability of the simple instruments necessary for the observational 

program. I hope that those of you who find 

this proposal of interest will write to Prof. 

Tison and obtain copies of the suggested plan.

The Vigil Network might well become the 

nucleus of an even broader program of international cooperation in hydrology the proposed International Water Decade being considered at Athens this month by the International Association of Scientific Hydrology.

The problem of climatic change,particularly in the arid zones, is that it alters the 

interrelationship between man and his natural 

environment. But it also affects the relationship between a man and that small segment of 

the earth where he lives. The problem of 

climatic change, insofar as it affects the use 

of natural resources, therefore affects each 

man on his hill. In making a suggestion, 

therefore, for a simple, practical, and inexpensive series of observations which may in 

some small measure further the cause of research in the arid zones, I would make a general plea to simplify and generalize the other 

aspects of arid-zone research activity with 

which we are all concerned. International 

programs often concentrate on means that 

are indirect, costly, and sufficiently abstruse 

that they do not seem to bring to a man on his 

hill any idea of his relation to the environment. We may do well to direct our attention 

to more widespread, simple, and inexpensive 

forms of communication to reach more quickly 

more men and more hills.

 ft U. S. GOVERNMENT PRINTING OFFICE : 1967 O - 274-090