Underground Rivers - University of New Mexico

Chapter 2 -- Greek Philosophers
Aristotle criticized Plato’s subterraneous reservoir theory, noting that Tartarus would have to be
impossibly large.
But if anyone will picture to himself a reservoir adequate to the water that is continuously
flowing day by day, and consider the amount of water, it is obvious that a receptacle that is to
contain all the water that flows in the year would be larger than the earth, or, at any rate, not
much smaller.
Aristotle likewise rejected that streamflow was generated in upland lakes.
The fact that rivers have their sources at the foot of the mountains proves that the place
accumulates water little by little by a gradual collection of drops, and that the sources of rivers
are formed this way. It is of course not at all impossible that there do exist such places
containing large amounts of water, like lakes; but they cannot be so large as to act in the way
this theory maintains, any more than one could reasonably suppose that their visible sources
supply all the water for the rivers, most of which flow from springs. It is thus equally
unreasonable to believe either that lakes or that the visible sources are the sole water supply.
Aristotle recognized that vapor from marine evaporation causes rainfall.
Now the sun, moving as it does, sets up processes of change and becoming and decay, and by
its agency the finest and sweetest water is every day carried up and is dissolved into vapor and
rises to the upper region, where it is condensed again by the cold and so returns to the earth.
He likewise recognized the principle of a hydrologic cycle.
For according as the sun moves from side to side, the moisture in this process rises and falls.
We must think of it as a river flowing up and down in a circle and made up partly of air and
partly of water.
Aristotle looked upon cool mountains as the site of direct condensation. The water so condensed
was then held by then like water in saturated sponges to be gradually released in springs.
The process is rather like that in which small drops form in the region above the earth, and
these join again others, until rain water falls in some quantity; similarly inside the earth, as it
were, at a single point, quantities of water collect together and gush out of the earth and form
the sources of rivers. A practical proof of this is that where men make irrigation works they
collect the water in pipes and channels, as though the higher parts of the earth were sweating it
out.
Similarly, the majority of springs are in the neighborhood of mountains and high places, and
there are few sources of water in the plains except rivers. For mountains and high places act
like a thick sponge overhanging the earth and make the water drip through and run together in
small quantities in many places. For they receive the great volume of rain water that falls... and
they cool the vapor as it rises and condense it again to water.
The question becomes, from where does such water rise?
According to Aristotle, it rises from both below and above the earth. Keeping in mind that
Aristotle did not distinguish between air and water vapor,
It is unreasonable for anyone to refuse to admit that air becomes water in the earth for the
same reason that it does above it.
The air surrounding the earth is turned into water by the cold of the heavens and falls and
rain... The air which penetrates and passes the crust of the earth also becomes transformed
into water owing to the cold which it encounters there. The water coming from the earth unites
with rainwater to produce rivers. The rainfall alone is quite insufficient to supply the rivers of the
world with water.
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