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   THE complete understanding, classification and use of the shapes of land for agricultural advantage is, along with climate, the basic structure of Keyline.

   The shape of our land as it is today has been determined by climate which moulded and modified it. The movement of water over land is a constant force. If this force with equal volume or power acts on land of uniform hardness and erodability, then it produces various shapes that possess constantly repeated and geometrically uniform patterns. But the differences in rainfall and run-off rate on the widely-differing basic geological shapes of land, and the degree of hardness and erodability of its structure, have produced, together with other climatic forces, what appears to be an infinite variety of land forms yet which lie within a few basic geometrical patterns.

   The variety of these shapes and patterns as they are produced in areas of similar climate, but on different geological bases, displays distinctive forms according to the geological structure beneath the surface. The large low forms of the soft granite country are very distinctive. The land could be classified as granite from its shape or outline alone from as great a distance as can be seen by the eye.

   Granite country often increases in hardness as it approaches an area of geological change and the gradually-changing form of the country may clearly indicate the approach of the major geological break. How often does one reach the top of a hill to see a complete change in the shape and form of the land. While granite country, with great rounded hard domes appearing, changes from the large low form to the small, steeper, harsher shape, it is succeeded by a new shape. It is wide, gentle, expansive, probably with a soft shale base. We look at the skyline--the profile of the hills--and see from their lines that it is a soft, sedimentary formation. At the same time we may note if it is lying horizontally or well off the horizontal plane. The profile of the hills may change again. They may be flat-topped, in line and the same height. Almost anyone may pick this as old basalt flow country.

   There is no doubt that the broad, wide view of land could be classified with the various major shapes related to their geological form. Some mining men and geologists develop a facility for judging these matters, but this particular study of land shape could be extended to a new agricultural study. I have noticed that farmers with mining experience tend to think of the potential of the land against its mineral and geological background.

   Our interest in land shape is agricultural. We are looking for agricultural advantage in this study. Can we find a unit area suitable for observation? Can we find a logical start or finish, or beginning and end, to a suitable land form? Now since water is a major factor in the final shape of land, we may reasonably begin by studying the behaviour of water flow on land surfaces.

   Progressively more run-off water flows over land from the centre of the ridge or hill to the centre of the valley. This is true whether we refer to the watershed of the smallest valley or the valley of a major river. But agriculture is the intimate use of the land and the water which falls as rain on the land, with man in close partnership. Therefore our consideration should start with the smallest valley and not with the watershed of the river.

   Run-off water caused by heavy rainfall has a path or a pattern of flow according to the shape of the land over which it flows. Every hill or ridge on which run-off water flows, directs by its shape the path of the run-off water to its first place of concentration, and here at this first concentration of water is found the first feature of land shape. It is the smallest valley and it is called "the primary valley" in Keyline. This valley is a rounded or grassed valley down which the first concentration of run-off water flows to join another valley or flowing stream. As water flow is the guide in this examination of land shape, then the area of land from which run-off flows to the primary valley is the first or primary catchment area, and it will be classed in these pages as the "primary land unit".

   There is a definite boundary to the catchment area of the primary valley where rain falling only inches away will flow to another valley. This boundary line is the centre or high line of a ridge.

   In this new approach I classify the centre line of the hill or ridge as a "neutral line of no flow" and the start, beginning or boundary of a land unit in relation to water. The "neutral line of no flow" has been referred to in the past as a water divide or water parting. Accepting run-off flow as the guide, then the bottom or end of this land unit is found where it meets another stream of flowing water. This second flow may also be in a valley of rounded shape or it may flow water in a confined stream with banks on either side such as a creek. This, then, is the end or finish of the primary land unit.

   The lateral boundaries of the primary land unit are the neutral lines of no flow of the ridges on either side of the primary valley. These smaller ridges, sometimes referred to as spurs, differ from the main ridge which carries the steep heads of the primary valleys, and will be named "primary ridges".

   We now have a land unit with both a start and a finish. Its upper limit is the main ridge, its sides are the primary ridges and it ends at the valley or stream course below.

   A start and a finish indicate that land can have length, e.g., length of slope. There will be all lengths of land, but for convenience these may be classified into short, medium and long. Short-length land may indicate a distance of one quarter of a mile from the neutral line of the main ridge down the valley to the line of the watercourse below. This is the length of land at "Nevallan" where Keyline originated. Where the distance is one mile this is medium length. Long length land may be two or more miles. Again, the length of land agriculturally signifies the unbroken length of the primary land unit from the neutral line of its main ridge to the first valley or watercourse below.

   The length of land as it exists now represents a balance of all the factors that have affected it from the past--climate, geology and vegetation.

   If the top of the main ridge is the start of a land unit, and the stream course below the end of a land unit, we then have agricultural land units that may be small in area or very large. In some shapes of country, the primary valley area or the primary land unit may occupy only an acre or two; in other types of country this same land unit may comprise upwards of one thousand acres. In the smaller form several associated units within one larger watershed may need to be grouped together to make a satisfactory agricultural working area or paddock. The larger unit may itself have to be subdivided to form suitable-sized paddocks. Indeed, some primary valleys may be too small to consider, but as these land features are to be used as guides for the planning and the working of the farm, then the primary valley must be given another quality or grading which may be called "significance". A primary valley which is too small or unsuitably shaped for a dam therefore has no planning "significance" if the plan of development includes the maximum conservation of run-off. It may still, however, have "significance" in Keyline cultivation. Again, it may be too small to enable the farm tractor to follow a cultivation pattern, and so loses all "significance".

   Within the area enclosed by the line of the top of the main ridge and the line of the stream course below, and bounded laterally by the neutral line of the primary ridges on either side, we have a section of land which may include all or many important agricultural shapes. Several primary valleys may fall from the one main ridge to the stream course below; for convenience two such adjacent valley areas or primary land units are included for examination. Our map then shows two complete primary land units, combining a part of the main ridge and including all the land in the watersheds of the two adjacent primary valleys. It is seen that the two primary land units now include two primary valley forms and a primary ridge form between them. Within this area of land, as seen depicted simply on the contour map, are typical shapes of ridge and valley: (1) the main ridge from which the two primary valleys form; (2) the primary ridge formed by the primary valleys on either side of it; and (3) the primary valleys themselves.

   The steep heads of the primary valleys fall or form from the main ridge shape; a primary ridge shape then is formed by and between the two primary valleys. The valleys have a standard geometrical pattern which can be seen in the contour lines of the contour map. The main ridge and the smaller primary ridge also have a regular geometrical pattern, again as seen in their contours. There is a typical geometrical pattern in the ridge form and there is a different but typical geometrical pattern in the valley form.

   These two general patterns in land shape are of great agricultural importance in the ultimate development of land by Keyline.

   There is an infinite variety of land shapes within these regular geometrical patterns of the contour of land, but if the significant features of the more or less regular forms depicted are fully appreciated, then all land shapes can be used to their best agricultural advantage.

   These geometrical patterns of land, as illustrated by their contours, are markedly consistent in a region of uniform geological character. A geological change may break the pattern, but it will generally re-form below the break until it finally ceases at the watercourse below.

   The primary valley form is probably the most important agricultural land shape. To repeat these points: It has a start in the main ridge where the steep head of the valley forms; it has its Keypoint in the valley bottom at the end of the steep head formation where the valley slope changes to form the second or flatter slope; it has a finish where the valley itself flows into a lower watercourse. It therefore has a top and bottom or high and low boundary.

   The primary valley also has a boundary on each side of it. Looking at the contour form of the primary valley below the Keyline, the points or the area where the contour lines on the sides of the valley are closer together forms the lateral boundary of the valley shape.

   The primary ridge shape between the two primary valleys in most circumstances is bounded by lines similar to those of the valley boundaries. This ridge has a top boundary at the top of the main ridge and a lower boundary at the stream course below. It has lateral boundaries represented by the boundary lines of the primary valleys on either side of it. The area of land on the sides of the valley where the contour lines are close together forms the line or boundary between the primary valley and primary ridge.

   The varying relative positions of this boundary between the primary valley and primary ridge on differing land shapes enable us to make two further land, shape classifications. These are "valley shaped" and "ridge shaped". Where the boundary is close to the valley the land is classified as "ridge shaped", and where the boundary is towards the neutral line of the primary ridge the land is "valley shaped". In a land form that is dominantly valley shaped the boundary up and down the ridge--where the contour lines are closest--will sometimes fall along the neutral line of no flow of the primary ridge. In this form the horizontal interval between the contour lines in the valley--below the Keyline--gradually become closer together as they leave the valley, reaching their narrowest point in the centre of the ridge; then the contour lines gradually widen out, reaching their greatest distance apart again in the next adjacent primary valley. In these circumstances of land shape the whole of the land is classified as valley shaped, with the neutral line of the primary ridge forming the boundary line between the valleys. (See Fig. 3, Upper )

   In the variety of these forms the boundary of the primary valleys may be anywhere from the neutral line of the primary ridge to close against the valley.

   These geometrical patterns, as displayed in the contour illustrations of land, will influence decisions on water conservation, farm roads, timber clearing, tree planting, cultivation procedures and much of the general working and management of the property.

   As stated earlier, the land forms may be very large or very small. And again if one primary valley form is too small to be of significance for water conservation--too small for a dam--it may still be large enough to have significance in cultivation patterns. Valleys smaller again may have to be completely disregarded because their size is such that they are too small within their natural boundaries for a valley pattern of cultivation. In these last circumstances, the very small valleys are disregarded in planning, but, in the cultivation or the treatment of land, the operator may consider them by slightly altering a plowing pattern. Such a valley may be a small tributary valley to a slightly larger primary valley. The valley form that still has significance as far as a cultivation pattern is concerned may not have significance as a water conservation valley.

   The man who puts in Keyline on his property may make many decisions of this nature in his early planning, but once he grasps the basic concept that the whole is more important than the part, these decisions will give him no difficulty. For instance, water supply is third on the Keyline scale. If this involves, in his circumstances, farm dams for irrigation, then his planning decisions are directed by his primary valleys which have water conservation significance.

   Areas of land may be considered as dominantly valley shaped, that is in the circumstances where the boundary of the valley or the up and down hill line through the points where the contours closely approach each other, are well away from the valley towards the centre of the ridge.

   Other areas of land may be considered as typically ridge shaped where the natural valley boundary is closer to the line of the bed of the valley. A very large ridge may be enclosed then by the boundary line of a valley on each side of it. The typical shape of this type of ridge has ridge sides which become steeper towards the valley floor. The sides progressively flatten out away from the valley to the neutral line of the ridge. Their typical contour pattern is illustrated by even-shaped sweeping curves in their contour lines, which are close together near the valley on either side of the ridge and gradually become further apart towards the neutral line of the ridge. This land shape is one of the basic geometrical patterns. It is of outstanding value as irrigation country in any circumstances where appreciable volumes of water can be made available near the middle length of the up-and-down slope.

   This precise Keyline classification of land shape for agricultural purposes is my own. It has been necessary for me to apply suitable names to the various units. The names are therefore new in this application. New names were not selected for the sake of being different but because there were no land classifications or names suitable for my purposes. Land sciences, such as Geography in its various branches, Geology, Morphology, Geomorphology, Hydrology and others, cover wide fields all associated with land shapes, but they do not provide a suitable nomenclature for the intimate study of land in Keyline. These sciences are chiefly concerned with the origin and development of major land surfaces and continental structures. Rivers and their valleys are examined, measured and classified. Their slopes and thalwegs are related to major works for dams, roads and railways. But the more general the concept the less the description and descriptive name is applicable to the specific smaller unit which is a fundamental in the Keyline concept.

   In my approach I have taken the smallest significant feature of land shape, which is the rounded, grassed or smooth valley of the farms, grazing lands and forests and called it the "primary valley". This unit includes the two slopes of the valley, the first steeper slope from the ridge in which it forms and the second flatter slope below to the watercourse where it ends. This primary valley is a gully to many, a re-entrant to others, a secondary valley, a headwater valley, and many other more picturesque names. But to take one of these names, headwater valley, which seems to be descriptively suitable, in many references it indicates the mountain catchment of rivers. This headwater valley then may have a catchment area of up to 1000 square miles and contain 10,000 to 20,000 primary valleys.

   In Keyline the first land shape then is the primary valley.

   This was considered from the point of view which is indicated by water flow. The area of land around the primary valley which sheds water to it then becomes the primary agricultural land unit, and it finishes at the stream course below, the lower boundary of the primary land unit. The primary land unit is synonymous with the primary valley area or primary valley watershed.

   The purpose in selecting a primary land unit is to examine the wider aspects of agricultural land in a small representative unity.

   The primary valleys of several primary land units may fall into the watercourse of a larger valley named a "secondary valley". The top boundaries of the watersheds of the primary valleys combine to form a catchment area whose boundary is that of the secondary valley area, and thus the secondary land unit. Every point in the secondary land unit is a point in a primary land unit. Other primary valleys flow from adjacent hills and ridges directly to the larger creeks and rivers, and to lakes. By summation all agricultural land is contained in primary land units; therefore all agricultural land is represented in our primary land unit with the exception of stream beds.

   Every primary valley falls or flows from higher land--from the hill or the ridge. The ridge from which the primary valley falls is the most important ridge to that primary valley and generally of other adjacent or nearby primary valleys. It is therefore named the "main ridge". It may be large or small, high or low, and short or long, or any combinations. of these, but it is still the main ridge of those primary valleys which fall from it.

   Between two adjacent primary valleys lies a ridge having similar high and low boundaries to that of the primary land unit. This was named the "primary ridge".

   The boundaries of watershed or catchment areas, whether they are of the smallest primary valley or the largest river valley, are ridge lines. These are generally called divides, water divides, or water partings. Such names do not indicate any particular size but will be used in this text in their general sense for the larger areas of land. The descriptive term, "neutral line of no flow" was used in describing these divides when they belong to the primary and secondary valleys of this study. The shorter term "neutral line" will generally be employed in relation to the divides of these two valley watersheds.

   These are the new land classifications and the names of the agricultural land features. I hope they may be found suitable for general agricultural use.

   The final significance of land shape will become increasingly apparent with the further description of the various Keyline techniques.

   In farm planning, the natural length of land is to remain stable. It must not be shortened by planning or farming practices which would cause more water flow and higher velocities. These may break the land in a new place, forming an erosion gutter or gully.

   The final shape of the primary valley itself, the rounded, grassed or timbered valley which the farmer can travel with his farming equipment, was formed by the balance of influences that collectively affected it, but most of all by water flow. It could be said to have been designed, constructed and developed with infinite care by a wide variety of natural forces, to perform the special function of draining the surrounding land and transporting the excess water to the watercourse below. It was built to transport the water which the climate and the surrounding land gave to it. If man, in his occupancy of the valley and the land about it, does not deteriorate the valley environment, then the valley will continue to perform its function and remain stable indefinitely. If, as is the aim in Keyline, the environment of the valley is improved by building the fertility of its soil and the soil of its surrounding catchment area, the valley continues stable and permanent; it is more capable of handling water and in even greater quantities than that supplied by the climate.

   When land is cleared there is likely to be slower and less absorption of rain into the soil, thus causing water to concentrate quicker and flow faster in the valley. But there are two reasons why this must be prevented. One, the valley stability could be affected, and two, more and longer-lasting moisture is needed in the soil of the whole of the land unit for its development and for the growth of grass and crops. The object is for all the soil to improve in fertility. The extra moisture in the soil should be evenly spread throughout all the land of the valley area.

   Now rainfall is uniform over the primary land unit, as it falls evenly enough to satisfy the desire for uniform moisture, but immediately rain reaches heavy run-off proportions the volume of water moving over various parts of this land unit varies. It follows its natural flow path, which is governed by the shape of the land. The volume of flowing water progressively increases from the neutral line of the ridge to the valley floor.

   We have already seen that straight-line or round-the-paddock cultivation crosses the natural flow lines of water in such a way as to cause earlier concentration and faster movement of the water to the valley. We may disregard for the moment, the sometimes increased absorption of rain into the soil from special types of cultivation. It is apparent that the natural flow pattern of water should either be preserved by the furrows left by cultivation or controlled in such a way as to spread flow water more uniformly. That is also true in the immediate area of the valley floor, where the wider spread of water reduces destructive velocities. However, our approach to water is not the negative one of preventing destructive velocities because it may cause soil erosion, but from the positive aim of controlling water to provide all the soil with its full requirements from each rain for the continuous improvement of the soil's climate. By spreading moisture uniformly and so controlling the type of run-off flow, thus making its path broader in the valley, we are, incidentally, effectively protecting and preserving the shape of the land.

   A diagram depicting the flow pattern of water on any shape of land can be produced on a suitable contour map by drawing lines outwards from points at equal distances along the neutral line of a ridge, and crossing each contour at right angles.

   A little thought will demonstrate that this is sound reasoning. Water flows downhill by the easiest or steepest path until it reaches a depression or valley and then it concentrates as a stream. The steepest path from any point on one contour of the map to the next contour is the shortest line from that point to the lower contour. The flow lines on the contour diagram therefore represent the path of the sheet flow of water over that land surface. In my studies of the flow patterns of water over various land surfaces I have discovered that the complete pattern, i.e., the flow pattern from the neutral line of the primary ridge to the bottom of the primary valley, always forms a flat S curve. Whether or not this fact has been recorded earlier by others I do not know, but I have been unable to find any reference of it. If ordinary cultivation procedures are employed, the flow path is steepened, thus causing water to concentrate earlier and to flow faster. It is therefore desirable to seek some other plan of cultivation that will distribute flow water evenly.

   Contour cultivation, theoretically, is cultivation that leaves a pattern of all furrows on the true contour. However, every run of the tractor and plow would need to follow a true contour line marked on the land with a levelling instrument or the land must be of perfectly even slope. Contour cultivation, as practised, is neither of these. It is simply a cultivation in the spaces between contour lines that have been levelled-in and marked on the land by permanent or semipermanent furrows or banks. It leaves a pattern of furrows half parallelling up from the lower contour and half parallelling down from the marked contour above. This pattern is illustrated on our map-diagram, which is a contour map of an actual land form, typical of country with a medium but not hard rock base. It is granite type country.

   The pattern of practical contour cultivation is illustrated by the broken lines each representing many actual furrows on the land. Arrow heads on the lines illustrate the downhill direction of the furrows. Furrows without arrows may be accepted as contour lines.

   It is seen that half the lines with arrows fall downhill in the general direction of the flow path and of the valley, thereby tending to cause earlier concentration of run-off and faster flow to the valley. An approximately equal number slope downhill in the opposite direction and away from the valley, opposing the flow lines, causing the run-off to spread as required. Contour cultivation is therefore much better than straight-line or round-the-paddock work.

   Keyline cultivation, however, produces a pattern of furrows in which all, or a very large majority, break the natural flow pattern of water over land surfaces in such a way as to reverse the direction of flow. The result is a wider and uniform spread which prevents quick concentration of flow water. The natural valley flow is always reduced and widened.

   As long as the influence of land shape on the flow path of flowing water is understood, it becomes a simple matter to control and evenly spread water by this Keyline technique. This knowledge influences many decisions.

   If true contour cultivation were practical, each furrow would then cross the water flow path at right angles and there would be no tendency to alter the flow path. Water would be held on the land longer by the fact that it would have to surmount the obstruction of each furrow at right angles to the flow path, but when general flow occurs, it still follows the natural flow lines.

   The Keyline conception of land shape is based on the fact that the consistent final force--flowing water--which shaped land, produced regular geometrical shapes in the land. The varieties of base hardness and the erodability of land and the varying amounts and times of water run-off produced infinite varieties within these geometrical patterns. The longer the shaping of land by water has continued the better are the shapes and the more valuable agriculturally. Since Australia is of great age geologically its land forms for a great period of time were very similar to its land forms today.

   There is another primary valley shape in Keyline and it is closely related to the first shape already discussed and which with its surrounding land was classed as the most important unit for agricultural study. Reviewing the first type of primary valley we concluded that it starts from the main ridge and finishes where the rounded primary valley flows to a stream course below. This primary valley within a stabilised geological formation is one of the consistent geometrical forms as seen in its contour lines. The other type is the valley that flows from a saddle or low point in the ridge.

   We have seen that the primary valley of the farms and grazing properties is a land form that transports run-off water over a rounded surface to a lower stream course, which may be a rounded valley or yet a creek or a river. The primary valley was formed and shaped by the work it does. For water to flow, the valley bottom must be lower than the land on each side of it at right angles to the direction of flow, or it would not be a valley and would not transport water. If the valley forms from a line of hills it must first lose height steeply, more steeply than the hillside. Then it flattens and flows more gently. The valley has a steep head, then a flatter bed. The steep head is generally of uniform slope until it flattens to form the flatter bed, which is the second slope of the valley. This second slope--more generally than otherwise--tends to continue as a uniform slope to the stream course below. This type of valley then has two slopes, one, the steep slope from the hill, and, two, the flatter valley floor slope below. The point of change between the steep head slope and the flatter valley floor slope is the keypoint of the valley, and the contour or grade line through this point is the keyline of the valley. However, the second type of primary valley forms from a saddle between two hills or a low point in a ridge.

   It does not have two slopes, but only the second slope, the flatter valley floor slope. This type of valley, by starting in the saddle, has already lost height. Its bed is already lower than the land on either side. It therefore may fall from the saddle as one continuous even slope. The saddle point is the keypoint of such a valley and the keyline is the contour or grade line through this point. (Fig. 7.)

   This valley, the one slope or saddle valley, has its keypoint at the saddle, but this keypoint is also the keypoint of another valley falling on the other side of the saddle. It is therefore a dual valley formation, with the two valleys falling in opposite directions from the one saddle or keypoint. This natural land form, and it is by no means uncommon, can be of outstanding agricultural value.

   It does not exist on either "Nevallan" or "Yobarnie", and was not mentioned in my earlier book, "The Keyline Plan". While I was aware of it then and saw in it the inevitable pattern of the land forms of Keyline, I had no opportunity to use it agriculturally. Of our three newly-acquired properties, two contain wonderful examples of these dual saddle-valleys in valuable agricultural form.

   A dam in such a valley would have the minimum of natural catchment, but if it were located with the top water level right to the saddle keypoint and designed and constructed as discussed and illustrated in later chapters in this book, it could have as many as four Keyline water conservation drains, each falling from different directions to the saddle and spilling into the dam.

   We have two such dams now on "Kencarley", Orange, N.S.W. One has a depth of twenty feet of water at the outlet valve of the dam. The wall of the dam provides three feet clear of freeboard but no spillway. The saddle itself is the natural spillway. When the dam overflows, the water runs out through the saddle into the other or second valley of this land formation and finishes up in a large reservoir in a valley a quarter of a mile away. The dam is of seven million gallons--28 acre feet-capacity, and although the reservoir nearby is nearly four times its size, our visitors all appear to be much more interested in this saddle Keyline dam.

   There are also primary valleys which form from a saddle but still have the two slopes, a steeper head slope from the saddle down to a point of change (the keypoint), and then the flatter valley slope below. This latter valley is of the same class as the first of the two primary valley shapes.

   To recapitulate: The particular geometrical form of the first type of primary valley, the commonest one in my experience, is seen in the contour map of the valley. Above the keyline of the valley the distances between contours in the valley are shorter than the distances between the same contours on each side of the valley, also the centre valley slope is steeper than the slopes on each side of the valley. Below, the keyline of the valley this relationship is reversed. The distances between the contours in the valley then are greater than the distances between the same contours on each side of the valley, and the slope down the valley bottom is flatter than the slopes on each side of the valley. Again, above the keyline the centre slope is steeper than the slopes of the sides, and below the keyline the valley is flatter than the sides.

   The saddle keypoint valley only possesses the second relationship, that of flatter valley bottom with steeper valley sides.

   Keyline Cultivation and Valley Shape : In order to spread water and moisture wider in the first type of primary valley by a cultivation that produces furrows opposing the natural flow pattern of water to the valley, it is only necessary to plow parallel with the keyline up the slope of the land and parallel with the keyline down the slope of the land. This is Keyline cultivation as it applies to this valley.

   All cultivating implements make a series of parallel lines or furrows on the land surface. Cultivation which parallels a line marked on the land as a contour remains, as cultivation proceeds, parallel to the contour on the surface plane of the land, but not to it on the vertical plane. Keyline cultivation uses this fact as a device and from a selected contour line previously marked out on the land plows in parallel formation in such a way that all furrows, or the great majority of furrows, oppose the natural flow paths of water on that particular piece or segment of land, thereby spreading the water or moisture more uniformly. Or more broadly still, Keyline cultivation is one that generally parallels a contour in such a way that water and moisture is caused to move as the farmer plans it for the good of his land.

   Always the general effect of Keyline cultivation on rains which are fully taken in by the soil is that the moisture is more uniformly held in the soil; there is no pronounced drift of moisture to the valleys. With rain that produces run-off, moisture is uniformly held, run-off is wide and flat, and the first concentration that flows in the valley commences lower down the valley. The flow is very much wider and shallower, velocities are cut to the minimum and the valley stability is progressively improved. Erosion of fertility and of soil is therefore not a factor for special consideration in Keyline agriculture.

   A Keyline appreciation of the various land shapes enables a farmer to control all aspects of water almost at will. The accumulation of power to control water which is provided by many hundreds of little furrows, all combining for one effect, is unbelievable until it is seen. For instance, following a very heavy storm which fell during the severe flood rains of 1956, one of our lower dams on "Yobarnie" overflowed with a stream two feet six inches deep by about fifteen feet wide through the flood spillway which emptied into a small flat valley. The valley was in a paddock which was Keyline cultivated three years earlier as a part of an experiment. The experiment, which included two other paddocks, was to determine the different effects on soil and pasture development of Keyline cultivation; one cultivation in the autumn for one year, one in each autumn for two years, and one each autumn for three years. This paddock, cultivated once only, had been stocked on and off about twenty-five times in the three years. There was no noticeable Keyline cultivation pattern left, as the stock had tramped it out. But within a few feet of the spillway's outflow in the valley the old Keyline cultivation patterns had completely controlled this large water flow. The powerful cumulative influence of what was left of the Keyline pattern spread the water well over three hundred feet wide. The water flowing in the valley centre was not noticeably deeper than that flowing on the sides of the valley where it extended laterally almost to the ridge between this valley and the next.

   One place where water never flows naturally is down the middle of a ridge, the neutral line of no-flow, in even the heaviest run-off elsewhere. But a Keyline cultivation designed for the purpose of carrying water down the centre of a ridge will control the water and cause it to flow there.

   Water can be induced to flow where it is wanted and as it is wanted--except uphill--if our treatment and management of land is based on a full appreciation of land shapes. And if water is the critical factor by being in short supply or by unreliable rainfall, then the simple logical approach is not to waste it. However, there was, until Keyline, a serious drawback to this obvious approach. There has been no way of conserving all the run-off profitably. But in water we have our greatest primary commodity. Water, within itself, can be used for its own distribution. A sound knowledge of land shape, implicit in the complete study of Keyline, enables one to harness the force of flowing water for its uniform distribution over agricultural land.

   We will assume for the moment that special Keyline techniques supply the cheapest means of distributing irrigation water in the manner most suitable for farms and grazing properties, and proceed to examine land shape as an aid in conserving all the run-off rain, but first consider briefly dam size and the possible cost of water storage.

   Water can be conserved almost anywhere on agricultural land; it is just a matter of cost. The higher the storage the more valuable is the water. just how much can a farmer profitably afford to pay for water storage capacity under conditions that permit economical use of the water for irrigation and in conditions where run-off is satisfactory? I do not know the limit of the amount he can afford to pay per acre foot of capacity, but the highest cost on any of my own farm irrigation dams is below £50 per acre foot, and this cost under the circumstances stated above is sufficiently attractive to warrant the outlay to conserve all the available run-off. By comparison the lowest cost of any of our dams was £6 per acre foot, on prices and values at time of writing.

   The cost of water conservation in farm dams is the least of the consideration in most so-called supplemental irrigation projects. Other costs such as pumping and equipment and labour are the critical ones. This has been said often before, but it is worth repeating in this context.

   If the cost of water storage capacity to hold all run-off and the cost of using the water returns a much higher profit than rain, or rain plus supplemental irrigation, then all water should be conserved.

   To return to dam sites: The possible conservation sites should be examined starting from the highest to the lowest sites. Here again the land formation of the primary valleys is of major importance.

   The highest valley water conservation site is generally just below the keypoint of the primary valley, thus leaving perhaps less than 20% of the slope above the keypoint. These sites were not considered for farm irrigation dams, because of their restricted natural catchment, until I started in 1944 building farm dams of from fifteen to forty acre feet capacity and providing special water conservation drains to fill them. The steep head of the valley above these sites--the true keyline dams--is usually short and collects only comparatively small quantities of flow water. Where the keypoint is a saddle point, the natural catchment of the true keyline dam would be still more restricted.

   Now the keypoints of the adjacent primary valleys in a common watershed such as a secondary valley are higher as the land rises. The primary valleys themselves form in the main ridge, so that normally as the country rises the heads of adjacent valleys are higher and the keypoints of the valleys are higher. In a series of primary valleys flowing into a larger valley or into a creek, in undulating country of uniform geological formation, the keypoints of the valleys generally have this rising relationship to each other. But before going on, a definition of "general land slope" is necessary, and so in our primary agricultural land unit, with its lower limit at the stream course or the creek below, the slope of the land is the fall from the main ridge down the primary valley or primary ridge to the watercourse or creek. General land slope, however, is the direction of the rise of all the land--the hills and the stream course--and it is usually at right angles to the slope of the primary land unit. The general fall of land then is the direction of the drainage line which is the creek or the watercourse to which the primary valleys fall. This direction is down land. Up land is the opposite direction to this fall.

   A series of primary valleys flowing to a creek have a slope to the creek, but the creek itself indicates the general land slope.

   These aspects of land have a very important significance in any circumstance where all the run-off water should be conserved in farm dams for irrigation purposes.

   The rising relationship of the keypoints of the primary valleys within the one larger catchment area, and in converse a falling relationship, enables the siting of a higher series of dams in such a way that all these dams can be filled by the water conservation drains before any run-off water gets away from the higher country. Slightly more catchment area is turned into the highest dam of he series, so that it will fill quickly. The overflow of this dam is directed into the catchment area or the water conservation drain of the next lower dam of the series, and so on down the series of keyline dams.

   As a general Keyline rule, all drains, both water conservation drains and irrigation drains, flow or fall with the general fall of the land. (See Fig. 9 )

   The contour map shows a series of primary valleys falling to the one creek. The direction of flow of the creek is the general fall of the land-down land. "Up the creek" is the general rise of the land-up land. The contours are seen to cross the creek as arrow heads or V's pointing upstream-up land.

   A study of these contours will show further that if water is to be brought into any of the farm irrigation dams, the conservation drain should be constructed from the dam rising in the direction of the general rise of the land. As the land rises, increasing land area lies above the drain to shed water to the drain for conservation in the dam. If the drain were to rise from the dam in the direction of the general fall-down land, then the drain would soon reach the top of the watershed, enclosing very little land which would shed water to the drain and so to the dam.

   This principle of water conservation drains rising up land always applies in the design of drains and their location in respect to water conservation where natural valley catchment is to be greatly increased. The only likely departure from the principle would be near property boundaries where the next land form is on a neighbour's property. Except where these interruptions may occur, all water in drains, both water conservation drains and irrigation drains, falls with the general fall of the land. A drain falling with the general fall of the land is, of course, also rising with the general rise of the land.

   The reason for this Keyline rule is obvious. Study of the contour map shows that contours in the down land direction have increasing land area below them as they are followed from the watercourse; in the opposite direction, from a ridge to the watercourse, the contours have decreasing land below them and soon reach the creek. Irrigation drains, which have a fall in the down land direction have increasing areas of land below them which can be irrigated by Keyline flow methods. If their fall were in the opposite direction there would be a rapidly decreasing area between the irrigation drain and the creek. There would be insufficient land for irrigation.

   Once the eye becomes trained to these simple land shapes, and the mind has selected and classified one or two of them, there is a fascination in the continuous broadening of one's understanding and appreciation of the landscape.

   Every trip I have in the country becomes more enjoyable, because of this added interest, and I have had the pleasure of seeing a like interest develop in many others.