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For this story we must go back in time. Twenty five thousand years, that is. Our little island looked very different then than now. It is a pity that there are no pictures available from that time that could give us a glimpse of the appearance of Curaçao. Scientific data, however, give a good indication that the earth was then in a so-called glacial period. This was a period during the ice age we are still in to a certain level, a period with a maximum amount of ice. At the time, all that ice was piled up by massive glacier systems, and much of Europe and North America was covered by a thick layer of ice. On Curaçao of 25,000 years ago, nothing was noticeable of that ice, nor the fact that the global climate was a lot colder. What was significant, though, was the fact that the level of the sea was much lower due to the absence of all that water which was transformed into ice. The sea level at the time was 20 meters lower compared to today! This situation has resulted in deeply cut gully valleys. How did those take shape?
Gully systems (rooien) are formed by rainwater, which always seeks the easiest way to get to sea. Assisted by sediment (disintegrated rock fragments with a grain size of sand and clay) that is washed along with the stream, the rocks over which the water flows are steadily eroded away, resulting into progressively deeper cut channels. This is a lengthy process that takes millions of years. The location where this process is visible to the extremes, is the Grand Canyon in the U.S.A. But also on our little island you get a good idea of what the process of erosion by rainwater does to the landscape. Those that climbed the Christoffel mountain, or any other hill on the Island for that matter, know that the landscape appears like sets of rolling hills. This is especially visible on Band’abou. The hills are interspersed with fairly deep grooves, all formed under the influence of the erosive action of rainwater, which for millennia has fallen and was transported to sea.
During the glacial period of 25,000 years ago, the gully valleys were eroded down to a pretty deep level, because of lower sea level, almost to the level where the runoff water actually ‘wanted to go’ (the sea level at that time). And then the ice melted, about 19,000 years ago, for not entirely understood climatic reasons. Less ice meant a significant rise in sea level. The mouths and lower reaches of the valleys were inundated, and the now so well known inland bays were born!
Rainwater causes even more changes to the landscape. A well known type of ecosystem on the island is called the Saliña. By the way, the Saliña area in the city was once the same type of landscape, although that is hardly noticeable anymore because the entire area has been filled in over time. If you look at the hinterlands of Daaibooi, Cas Abou, Knip and virtually all naturally formed bays, you’ll encounter a saliña. A drab gray-brown plain filled with clayey material which in the rainy season often is inundated. If we would have had pictures of thousands of years ago of these same locations, we would see a completely different landscape. In fact, these sites were nothing other than inner bays. Inner bays like St. Joris, Spanish Water, Schottegat, Piscadera and St. Martha. These inland bays were filled with seawater and were most likely fringed by mangroves. The bays themselves supported large seagrass beds, which were a (foraging) habitat for animals like fish, sea turtles and lobsters. Under the influence of rain, these inland bays changed in appearance and became what they are today, saliñas. What happened?
The origin of a saliña
As already mentioned, ‘rooien’ are carved out by the sediment which is transported by the water stream. This ‘abrasive’ attacks the rocks so that notches start to take shape. Just take a look at a flow of rainwater if you happen upon one. You’ll observe that the water is full of mud, stones and sand. Ideal abrasives. During grinding even more material is loosened which will further contribute to the erosive process. All these abrasives have to go somewhere, so they are transported with the rainwater towards the lowest point, preferable the sea level (or lower). In many cases, however, the end point will be an inner bay, because that is where most ‘rooien’ will lead to anyway (and because the inner bays were part of the gully systems in the first place). Through this continuous supply of geological materials, the inner bay becomes increasingly shallow.
However, in the sea there is also an ongoing process that contributes to the creation of a saliña. Chunks of limestone that are supplied by the sea, together with active coral formation, make sure that at a certain point in time the entrance to the inner bays gets closed off. No more fresh seawater gets in, and the isolated water inside the bay is more and more exposed to the sun. The sun’s rays heat the closed inner bay until all water has evaporated and only the salt from the water remains, mixed with the mud deposited by the ‘rooien’. A saliña is ‘born’. In rainy periods, as we are evidently in at the moment, during which the ‘rooien’ transport rainwater to the lowest point, those saliña’s, they’ll fill with fresh water. The existing salt dissolves in this layer of water. But because the amount of water will never be as much as there used to be at the time of the open bay, the salinity of the water will end up to be several times higher than seawater. A perfect environment for animals like brine shrimps and brine flies, which in turn attract many bird species, including flamingo (Phoenicopterus ruber).
Nature created a natural salt pan, and inspired man to create the salt pans as have been used for years on the island, in the past. They used existing saliñas and built low dams within those. Through specially dug canals and locks seawater was allowed to flow into these salt pans. They used sustainable and free solar energy to evaporate the water, and gathered the salt which in historical times was extremely valuable. Natural and historical processes that were all orchestrated by water!