FullReads

For remember that, from a point above Berber to the sea, the dwindling Nile never receives a single tributary, a single drop of fresh water. For more than fifteen hundred miles the ever-lessening river rolls on between bare desert hills and spreads fertility over the deep valley in their midst–just as far as its own mud sheet can cover the barren rocky bottom, and no farther. For the most part the line of demarcation between the grey bare desert and the cultivable plain is as clear and as well-defined as the margin of sea and land: you can stand with one foot on the barren rock and one on the green soil of the tilled and irrigated mud-land. For the water rises up to a certain level, and to that level accordingly it distributes both mud and moisture: above it comes the arid rock, as destitute of life, as dead and bare and lonely as the centre of Sahara. In and out, in waving line, up to the base of the hills, cultivation and greenery follow, with absolute accuracy, the line of highest flood-level; beyond it the hot rock stretches dreary and desolate. Here and there islands of sandstone stand out above the green sea of doura or cotton; here and there a bay of fertility runs away up some lateral valley, following the course of the mud; but one inch above the inundation-mark vegetation and life stop short all at once with absolute abruptness. In Egypt, then, more than anywhere else, one sees with one’s own eyes that mud and moisture are the very conditions of mundane fertility.

Beyond Cairo, as one descends seaward, the mud begins to open out fan-wise and form a delta. The narrow mountain ranges no longer hem it in. It has room to expand and spread itself freely over the surrounding country, won by degrees from the Mediterranean. At the mouths the mud pours out into the sea and forms fresh deposits constantly on the bottom, which are gradually silting up still newer lands to seaward. Slow as is the progress of this land-forming action, there can be no doubt that the Nile has the intention of filling up by degrees the whole eastern Mediterranean, and that in process of time–say in no more than a few million years or so, a mere bagatelle to the geologist–with the aid of the Po and some other lesser streams, it will transform the entire basin of the inland sea into a level and cultivable plain, like Bengal or Mesopotamia, themselves (as we shall see) the final result of just such silting action.

It is so very important, for those who wish to see things “as clear as mud,” to understand this prime principle of the formation of mud-lands, that I shall make no apology for insisting on it further in some little detail; for when one comes to look the matter plainly in the face, one can see in a minute that almost all the big things in human history have been entirely dependent upon the mud of the great rivers. Thebes and Memphis, Rameses and Amenhotep, based their civilisation absolutely upon the mud of Nile. The bricks of Babylon were moulded of Euphrates mud; the greatness of Nineveh reposed on the silt of the Tigris. Upper India is the Indus; Agra and Delhi are Ganges and Jumna mud; China is the Hoang Ho and the Yang-tse-Kiang; Burmah is the paddy field of the Irrawaddy delta. And so many great plains in either hemisphere consist really of nothing else but mud-banks of almost incredible extent, filling up prehistoric Baltics and Mediterraneans, that a glance at the probable course of future evolution in this respect may help us to understand and to realize more fully the gigantic scale of some past accumulations.

As a preliminary canter I shall trot out first the valley of the Po, the existing mud flat best known by personal experience to the feet and eyes of the tweed-clad English tourist. Everybody who has looked down upon the wide Lombard plain from the pinnacled roof of Milan Cathedral, or who has passed by rail through that monotonous level of poplars and vines between Verona and Venice, knows well what a mud flat due to inundation and gradual silting up of a valley looks like. What I want to do now is to inquire into its origin, and to follow up in fancy the same process, still in action, till it has filled the Adriatic from end to end with one great cultivable lowland.