With a volume of about 1,390 million cubic kilometres of water, the Earth is definitely the “blue marble” (as defined by the crew of Apollo 17 in 1972). Endless expanses of lakes, rivers and above all seas make our planet an aquatic landscape with opportunities and challenges. Among these, orienting oneself has always been among the greatest one for those who, in the past and not, decided to venture out to discover distant lands.
The methods used over the centuries to orient oneself in the water are innumerable: from the crows trained by the Vikings to look for the nearest dry land, to the tables on which the shadow of the sun was projected and the celestial vault was reconstructed: always the natural map par excellence.
How to read water
The stars, however, are not the only allies. There is a way, certainly more complicated but infinitely more poetic: “read the water” and let it guide us and indicate the direction.
It is the study of waves, their propagation and currents.
If for example you sail near a coast with rocks overlooking the sea, it is possible to observe at least two types of waves: one coming from the ocean and the other coming from the coast, a reflection of those that break on the rocks. The waves therefore indicate the presence of land.
It is important to know that in addition to the coasts, the seabed also plays a decisive role in the life of waves. If the slope of the seabed is steep, the waves break brutally and generate abrupt movements. If the slope is gentle, the energy of the waves gradually dissipates, generating gentler wave motions.
Mau Piailug, one of the greatest navigators in history, simply observing the waves had learned to identify up to five types and was able to guess where storms had formed, for how long and what their strength was. A life-saving connection with the surrounding environment.
An ocean of sand
However, there are other types of waves that populate a “sea” made of sand and not water: the dunes, which speak to some and confuse others.
In these Martian (for us) landscapes it seems impossible to orient oneself: there is no point of reference, not even a clue. Yet, in an apparently hostile environment, there are those who have learned to listen and observe.
Desert nomads, for example, use the shadow cast by camel ears to seek direction or, more frequently, they learn the songs of the winds and observe the drawings usually drawn on the sand.
Combining the knowledge of the direction of the air and its strength, together with that of the sand and its dance, they manage to obtain the crossing angle to be followed in order to reach the desired destination.
In these places it is natural to establish a spiritual approach, a deep connection with the “voice of the desert”. Dunes are not just crests of sand shaped by the wind (or by water, in the seabed), there are several studies investigating their interaction. It has been observed how the flows of air or water investing a dune system influence its communication, the movement of the front dune influencing and modifying that of the rear one. And then the song of the dunes, generated by the movement of the grains (and modulated by their size) that indicates the type of sand and the movement of the wind.
There are many clues that can reach our ears and stand before our eyes: nature and the landscape speak and show themselves to us. It is essential to know how to Listen and See.