Upstream

“ The course of water flowing underground is not strictly analogous to that of rivers on the surface, there being, in the one case, a constant descent from a higher to a lower level from the source of the stream to the sea; whereas, in the other, the water may at one time sink far below the level of the ocean, and afterwards rise again high above it. ”

“ The natural consequence is a stream of the most broken and impetuous character, a stream whose rushing, roaring, and foaming drowns all sounds contiguous to it; rapid after rapid of seemingly tempest-tossed and crested billows, of whirlpools and eddies, of backwaters and heavings into surface currents, and never a still pool to be found anywhere. ”

“ Then follows the elevation and tilting of the peneplain with the cover on its back; and with this regression of the sea, there is an equivalent gain of new land; a smooth gently sloping plain is revealed as the shore line retreats; streams run out across it from the crystalline area, or begin on its open surface, growing mouthward as the land rises. Three such streams, A, C, D, are shown in fig. 3; their opportunity for deep valley-cutting is indicated by the depth of the new baselevel, BL, below the general surface of the country. ”

“ OTHER WATER BORDERS It is the proper destiny of every considerable stream in the west to become an irrigating ditch. It would seem the streams are willing. They go as far as they can, or dare, toward the tillable lands in their own boulder fenced gullies—but how much farther in the man-made waterways. ”

“ Low, flat, sea-coast land, pierced by rivers, presents a very similar appearance the world over, where river current and sea-tide are not hemmed in by lofty barriers. Over the low land the sea washes, and in channels down to the sea from the higher levels the river “rives” its way. Gradually, as it approaches the sea, the bed becomes more horizontal, and the earth suspended in the water is as gradually deposited in the bed of the channel. ”

“ At our feet a stream was struggling with the multitude of rude rocks, which Nature, in one of her primeval convulsions, had flung here and there in masses into its current; sometimes uniting into irregular ledges, over which the water swept with impetuosity;—sometimes standing insulated in the stream, and increasing the energies of the river by their resistance;—sometimes breaking forward from the bank, and giving a bolder effect to its romantic outline. ”

“ Watched thy clear blue waters as they slowly pass by,
Reflecting true pictures of the clouds in the sky.
So deep is thy bottom and so broad is thy stream,
Thy volume is greater than thy looks make it seem,
Tho slow is thy current, great force there is in it,
Moving a million tons of water each minute.{120}
Many are the sources that provide the supply,
That keeps this great river from ever running dry,
The inflow and outflow do so nearly conform,
That the river’s level is very uniform. ”

“ Thus increasing to a degree approaching perfection, the purity and abundance of the crystal flood, that shall flow from a countless multitude of new springs of living water. The volume of water from these springs, shall furnish a supply sufficient to maintain with full channels, a perpetual flow in that net-work of lakes and rivers, that arterial system of fertility and commerce, which variegates and adorns the bright face of our fair land. ”

“ The streams that burst forth from every crevice are thrown, by the irregularities of the surface, into numberless cascades, often disappear in mists or in chasms, and emerge from subterranean channels, and, finally, either subside into lakes, or quietly meander through the lower and more level grounds. ”

“ And deep under the earth, hurrying toward the subterranean stream, were other streams, small and great, but all deep, hurrying to and from that great mother-stream underneath, just as the small and great overground streams hurry to and from their mother Mississippi. It was almost more than the little convent girl could take in: at least such was the expression of her eyes; for they opened as all eyes have to open at pilot stories. ”

“ Rivers which are forced by artificial barriers to flow in one channel, across a flat alluvial tract, to the sea, ever tend to raise their own beds, and the embankments, rising with them for the protection of the marshes, exhibit in the Po and the numerous rivers of Holland, and the English fens, the singular spectacle of vase volumes of water, flowing on levels many feet or yards above the cultivated fields, and even higher than the houses, which are often placed below the shelter of the dangerous bank. ”

“ The stream, at a vast height above him, is seen leaping from ledge to ledge,—sometimes lost, sometimes sparkling in sunshine, till it courses impetuously beneath the rock on which he is seated, and is lost in the deep unbroken obscurity of the forest. ”

“ A river that spreads out into the indeterminate earthform of a marsh is an effective barrier; but one that gathers waters into a natural basin and forms a lake retains the uniting power of a navigable stream and also, by the extension of its area and elimination of its current, approaches the nature of an enclosed sea. Mountain rivers, characterized by small volume and turbulent flow, first become navigable when they check their impetuosity and gather their store of water in some lake basin. ”

“ When a land surface rises from the ocean the stream systems which at once develope, are set the task of carrying back to the sea all that stands above it. According to the amount of this alloted work that streams have accomplished, they may be said to be young, mature or aged; and if, their task once nearly completed, another uplift raise more material to be carried off, they may be said to be revived. These terms apply equally to the land-surface, and each period of development is characterized by certain topographic forms. ”

“ A stream may acquire the name of a river, in the channel of which, at some seasons of extreme drought, no water flows. For a great portion of the year parts of a stream may flow in great abundance, in which, during a very dry season, we may find only standing pools. It would be against all usage to say that the general source of the river was at that point in its channel from which the water always flows. ”

“ Any newly formed land surface, like a recently drained lake bed or part of the marginal sea bottom which has been raised into land, has a drainage system developed upon it. In the early or youthful stage of such a new land area lying well above sea level, under ordinary climatic conditions a few streams only form and these tend to follow the natural or initial slope of the land. ”

“ If it shall be found that nearly all the rainfall should go into the soil and thence into the under-drainage, coming out slowly and steadily by seepage and by springs into the streams, clear and pure, these streams should present nearly ideal conditions for water-food, for water-power and for stream-navigation. An ideal solution of the soil problem may therefore solve the greater part of the whole complex of problems of which navigation is the last term. ”

“ But, frequently, a very large marsh is traversed by a tortuous stream which occupies a large area, and which, although the tidal water which it contains gives it the appearance of a river, is only the outlet of an insignificant stream, which might be carried along the edge of the upland in an ordinary mill-race. ”

“ The stream whose water spreads over its low banks is without depth and current and power. But confine the waters between high, narrow banks, the bed of the stream is deepened, and its mighty current supports animal life and turns the wheels of mill and factory. ”

“ When the tide begins to flow up the river there may be a low-level salt water current moving landward and a high-level fresh water current moving seaward, but this is quite a temporary state of affairs. The surface slope is landward, and the water moving seaward is not moving in obedience to the surface slope. ”

“ BRAIDED CHANNELS. A river actively engaged in aggrading its valley with coarse waste builds a flood plain of comparatively steep gradient and often flows down it in a fairly direct course and through a network of braided channels. From time to time a channel becomes choked with waste, and the water no longer finding room in it breaks out and cuts and builds itself a new way which reunites down valley with the other channels. Thus there becomes established a network of ever-changing channels inclosing low islands of sand and gravel. ”

“ When this mechanical power of running water is considered, we are prepared for the transportation before alluded to of large quantities of gravel, sand, and mud, by torrents which descend from mountainous regions. But a question naturally arises, How the more tranquil rivers of the valleys and plains, flowing on comparatively level ground, can remove the prodigious burden which is discharged into them by their numerous tributaries, and by what means they are enabled to convey the whole mass to the sea? ”

“ With favorable conditions, as a stream carrying abundance of fine silt, the water moving sluggishly over the inundated surfaces will drop its earthy burden upon them in thin, loose layers, evenly at first, but, as shallows are formed, irregularly modified, or as sudden freshets produce stronger currents, eddies and ripple-bars gather or disturb the sediment. New lands in wet banks and knobs will begin to appear over the highest ridges. ”

“ As the streams that flow on the surface of the earth are constantly altering their courses, thus also the subterranean waters are ever active in excavating new channels in the bosom of the rock. Finding at length new outlets on a lower level, they abandon their ancient beds, and the explorer now wanders dry-footed where once a foaming river gushed along. ”

“ Alteration of Depth or Water-Level.—When the width of a stream is altered, the depth of water—the gradient being supposed to be unchanged—must alter in the opposite manner. A narrowing of the channel by training necessitates an increase in the depth of water, and the same remark applies if an arm of the stream is closed. The increase in depth may be effected either by raising the water-level or by lowering the bed—as may be convenient—or both. If the bed is to be lowered and is of hard clay, it may be necessary to dredge it and, when this has been done, training may be unnecessary. ”

“ There are some great streams which are of first magnitude in all their characteristics—rivers which drain millions of square miles in their course to the sea. The number of such is small, however; there are scarcely fifty on the whole globe. Besides these, there is a large number of rivers much shorter, and of much less volume, but not deficient in the attributes which give a stream value to man, and which serve to mediate between highlands and lowlands, to fulfill the needs of navigation and to drain regions of more or less magnitude. ”

“ When a river is embanked at a given point, and, consequently, the water of its floods, which would otherwise spread over a wide surface, is confined within narrow limits, the velocity of the current and its transporting power are augmented, and its burden of sand and gravel is deposited at some lower point, where the rapidity of its flow is checked by a dam or other artificial obstruction, by a diminution in the inclination of the bed, by a wider channel, or finally by a lacustrine or marine basin which receives its waters. ”

“ Owing to a flow of upland water down a river the ebb lasts longer than the flood tide by a period, increasing in length as the distance from the mouth of the river increases; and, similarly to the sea, the current may continue to run down a river after the tide has turned and the level of the water is rising. ”

“ By far the larger part of the sediment acquired by a normal stream is made up of material loosened in advance by the processes of weathering. The stream, or the waters which get together to make the stream, find them ready-made; but rivers frequently wear rock which is not weathered, for the principal valleys of the earth’s surface are cut in solid rock, and many of them in rock of exceeding hardness. How does the stream wear the solid rock? ”

“ If the stream receives no water of another kind, or scarcely any, not only the rivers, but likewise the lakes which receive these waters, are of the same nature as the springs, and serve the same uses ”

“ An enlargement of the bed of the river, principally by deepening it, in order to increase its discharging capacity sufficiently to prevent inundations, is precluded by the cost, and also, in rivers bringing down sediment, by the large deposit that would take place in the enlarged channel from the reduction in the velocity of the current when the flood begins to subside. ”

“ These are the natural consequences which must follow if the land has long been worked upon by streams, and no other process has ever been suggested which is competent to produce them. We must conclude that valley systems have been formed by the river systems which drain them, aided by the work of the weather; they are not gaping fissures in the earth's crust, as early observers imagined, but are the furrows which running water has drawn upon the land. ”

“ In all geological times, as at the present, the work of streams has been to destroy the lands, and in so doing to furnish to the ocean the materials from which the lands of future ages were to be made. Before we consider how the waste of the land brought in by streams is rebuilt upon the ocean floor, we must proceed to study the work of two agents, glacier ice and the wind, which cooperate with rivers in the denudation of the land. ”

“ The mouth of a large river system is the converging point of many lines of inland and maritime navigation. The interests of commerce, especially in its earlier periods of development, demand that the contact here of river and sea be extensive as possible. Nature suggests the way to fulfill this requirement. The sluggish lowland current of a river, on approaching sea level, throws out distributaries that reach the coast at various points and form a network of channels, which can be deepened and rendered permanent by canalization. ”