Geoligic Fault
The regional geology is characterized by the presence of a series of flows. The term “flows” is the name used to designate volcanic rock that originally flowed in liquid state under the surface of a solid layer and then cooled becoming solid.
In the region many of these flows have been discovered - 11 distinct ones in Misiones alone. These flows have formed successiely on top of each other resulting in successive “mantles.” (It is important to note that the term “mantle” is used incorrectly here. “Mantle” actually refers to something else, however it will help one not versed in the subject to form a mental image).
These “mantles” have very similar physical and chemical properties, but can vary minutely in composition depending on the cooling process. Consequently, the erosive action of the falls upon these “mantles” varies as well and some are eroded faster than others. This is one of the factors responsible for the formation of Iguazu Falls as they are today.
Another factor is the presence of faults along the course of the river. Faults are when there is a fracture in in the earth's crust in which the rock on one side of the fracture has measurable movement in relation to the rock on the other side.
To visualize the phenomenon imagine a flat, horizontal plane. When a fault takes place, it creates a “step”, like a stair, that could be a few millimetres to some meters in size, depending on the intensity of the phenomenon that caused it. The river's slope, in its early phase was quite pronounced and the water “fell” off of these these steps (faults), having a much more erosive effect than in the areas without fractures. As a consequence, a depression starts to form immediately after the fracture.
The Iguazu river runs, at least in some sections, over a flow very resistant to the erosive action of the water. The layer beneath it, however, is appreciably more vulnerable to that action. With the passing of time the water erodes the lower layer, and with its support removed, the upper layer starts to crumble progressively.
Huge blocks can be observed at the foot of some falls – especially from the Argentinean side – these are the remains of the upper defile. The previous description explains that the water screen serves as a shelter for birds and amphibians.
As the erosion process continues “backwards”, over future millenniums the falls will keep moving, as they have been since time immemorial.
A SINGLE DAY IS NOT ENOUGH!
If you wish to visit the Park for two consecutive days, the 2nd day you can get a BONUS in the cost of your entrance. Here.
So that you can experience this unique natural spectacle in its entirety, we suggest 10 things that you should not miss inside the Iguazu National Park. Here.
"Truly a Wonder of Nature".
One of the most unique sights in the world, you have to experience it to understand its beauty. Stroll under the light of the Full Moon and dine in the La Selva Restaurant. Here.
