Biostasic and rhexistasic periods

Some time ago, Henry Erhart, author of "The genesis of soils as a geological phenomenon" traveled by ship crossing the Congo and Amazon rivers. 

Erhart was intrigued by the low turbidity of the waters. There were no sediments, no clays, nothing of the brown color that one can expect from large rivers draining such large basins. 

It was at that moment that he realized that the characteristics of these waters represented nothing more than the synthetic expression of what was happening in the upstriam river basins. The large fluvial courses came from basins of humid forests where there was no erosion. They were environments in which chemical processes of organic origin predominated.

Fluvial waters were exporting salts, invisibly, slowly but surely. The soils were losing their ions dissolved in the water towards the sea. However, there was almost no transport of any sediment. The cations of calcium, sodium, potassium, magnesium, silicon, carbonate anions, phosphates and chlorides were transported dissolved in the water in small proportions, but at the end of each year an impressive volume of salts was evacuated to the sea contributing to  gradually increase salinity of the seas or providing raw material for the shells or other components of marine organisms.

Erhart also realized that this was the origin of the geological limestones. These rocks were the result of old processes of pedogenesis (weathering) in humid forest environments. The current calcareous muds of the ocean floor are the equivalent of those ancient limestones that had formed 100 or 200 million years ago in the Mesozoic Era when dinosaurs roamed the earth.

However, these calcareous muds of the past had not continued to form eternally. We know that one day the calcareous sediments stopped forming and on top of them different sediments accumulated.

In rock sequences, first appear clayey, loamy (clayey-calcareous) and silty formations and later sandy materials (sandstones) were deposited. The set of these detrital sediments are called flysch. On top of them conglomerate units are found that are known with the name of molasses.

Erhart read the above mentioned “geological book” and concluded that this was an indication that the forest had disappeared and that the soil was beginning to be eroded.
There were also occurrences of orogenic ascents in the geosynclines and platforms that gave rise to the "continentalization" of the marine accumulation zones.

The presence of detrital materials was the result of soil erosion, and the increase in grain size was related mainly to the decrease in the depth of the seabed. The clays, marls and silts are deposited in shallow and medium depth waters, the sands in coastal waters and the conglomerates in the fluvial valleys that were formed after the emergence of the marine sediments.

The period of geological stability, in which the chemical alteration in the continents predominated, corresponded to the calcareous accumulations. He called it biostatic period. The moments of instability where the erosive processes and detrictic sediments dominated, he called it rhexistasic periods..

Today, as in other eras, many large jungles are disappearing. This time it is not because of natural evolution, of the kind that occurred periodically in geological history, but instead it is a process due to human action. Deforestation processes have become widespread. The forests are cut and burned, soils are eroded, the clean waters of the rivers are transformed into muddy flows. Flying over the Amazon River, every year we have new surprises. The tributaries turn yellow and brown. The Amazon River is no longer dark green. In geological terms, the forests are dying.

At other times things were different, some forests died but others were born and therefore there were always forests that helped to maintain stable CO2 levels. Today, all forests are disappearing at the same time. Undoubtedly, the effects will be multiple and perhaps irreversible. Although we cannot predict the details of the future evolution of the planet, it can be foreseen, without fear of being wrong, that something serious, perhaps irreparable, is brewing and will end up materializing if urgently we do not revert the direction of these processes.