The geological and geomorphological research carried out show the most relevant aspects of the development of this research project. The study was based on the analysis of existing information, processing and interpretation of remote sensors of multi-temporal imagery and projected into 3D terrain digital modeling, and three field trips between 2015 and 2017. This included the north and central region of the highlands (serranía) and rock, sediment and mineral analysis in outcroppings and wall painted areas using fluorescence geochemical methods and X-Ray diffraction.
The study, for the first time, helped determine the geological and geomorphological indicators related to cultural aspects of wall paintings based on lithological, mineralogical and geomorphological criteria. It also allowed obtaining a more geological and geomorphological cartography with greater detail (1:50.000) of those previously achieved.
The Chiribiquete National Natural Park has a total surface area of 27,823 square kilometers and is located in the Colombian Amazon region. In this area, the highlands cover a surface of 10,000 square kilometers, which the government recently extended in 1,486.676 hectares (ha) for a total of 4,268.676 ha.
One of the conclusions is that the national park is a great example of the stages of the history of the Earth, due to its geographical location, composition and geological structure of the westernmost part of the of the Guiana Shield. Given the geological, structural and natural erosion of the rocks, this region enabled the formation and preservation of unique ecosystems.
The high natural degradation of the highlands due to transformations of the structure of the earth crust (tectonic processes) combined with hydrological agents of past seas and current surface movement, have evolved to a great number and variety of geographic forms and marvelous isolated table-top mountains (tepuis) making this natural park a unique place in the world.
These particular elements allowed the Serranía de Chiribiquete to become a sacred and mythological location where several ancestral cultures registered their lives in spectacular and huge mural paintings on the rocks.
From the geological point of view, the Serranía de Chiribiquete is a tectonically raised block due to faults in the middle of the Amazon. The lithological composition is made up of igneous crystalline and metamorphic Precambrian rock on its foundations. The highlands rise on top of these rocks with predominantly sedimentary rocks of sandy texture and quartz composition. Locally researchers discovered levels of quartzites in the upper part of the geological formation (Araracuara Formation).
The main structural characteristic of the Chiribiquete great plateau or tepui is a stratification of layers placed almost horizontally. The presence of regional fractures that cross the mountain in different directions have repercussions in the formation of a great variety of exotic mountains.
The Chiribiquete National Natural Park has two geomorphological provinces:
The first has a surface of 10.076 km2 and is a great tectonic plateau with strong unleveled pieces of land and fractioned by water in numerous minor plateaus. These tepuis are directed predominantly to the south-north. They have maximum heights of 800 meters above sea level and relative heights (distance between the ground and the peak) of maximum 544 meters.
The park has a notorious increase of height of the plateaus to the north and northeast. Researchers think the Serranía de Chiribiquete was higher but relics of superimposed plateaus of close to five superior levels remained.
During this research project, they identified and mapped 13 geomorphological units related to the types of plateaus in the Province of the Serranía de Chiribiquete according to the form, size, relative height, absolute height, peak form and minor structures.
The highlands also have great diversity and exotic forms produced by water processes which eroded the land giving birth to:
These processes seem to have begun on the surface of the plateaus due to the effect of surface and underground water. They are recognized for their round forms and because of the presence of abundant plant life which contrasts with the surroundings. Afterward, with the breakdown of the higher portions of the tepui, residual chasms remained. Other tepuis developed concentric parallel borders.
The water wealth of the natural park represents its greater biodiversity due to the interaction between the atmosphere and the rock of the highlands. It is necessary to sleep and rise on the tepui top to understand this process.
The highlands do not have ground development; the surfaces of the plateaus are comprised of rock and the plant life fixes on top of fractures and cracks of the rocks. As the majority of these rocks are white quartzites sandstones, they reflect all the energy of the sunlight. However, due to the decomposition of the rock in coming into contact with the atmosphere (meteorization) and water washing, they form a thin layer between dark and black which makes the solar energy to be absorbed and make the surface hot.
During the dawn, when the temperature lowers, the moisture of the jungle rises due to the effect of the evaporation and transpiration of plants, this forms clouds around the tepuis, producing a spectacular sight of a prehistoric lost world.
When the sun rises and the surface of the rock warms, this vapor turns to liquid and makes the water to drip on the surface, forming great flowing temporary and permanent water streams and filtrations on the porous rock, exiting to the sides of the most accentuated slopes forming beautiful water cascades of different colors produced by the iron content dissolved from the rocks.
These characteristics make the Serranía de Chiribiquete one of the most important water reloading zones of the Amazon which feed several rivers such as the Apaporis, Caquetá and Tiuna rivers, among the most important.
One of the most relevant questions from the anthropology and social sciences point of view is why the Serranía de Chiribiquete has been considered as a sanctuary for ancestral wall and cave paintings and why not the largest and very well preserved plateaus of Venezuela and Brazil, such as the Roraima Park.
According to studies performed by anthropologists during the investigation, to the north of the highlands, they identified and studied close to 50 murals with more than 70,000 paintings.
Geological and geomorphological research showed relevant evidence which helped to answer the question, thanks to the analysis of the following indicators necessary for the existence of these wall paintings:
As a geographical place, the Serranía de Chiribiquete has a strategic position in the center of the Amazon for the passing of ancestral communities which traveled from the south to the north of South America and the Caribbean. It represented a sacred and transitioning location.
In order to perform painting on the rock, it is necessary for the rock to have certain composition and structure. Most of the rocks are from the Araracuara Formation and comprised of non-cemented quartz sandstones, granular and brittle which do not allow the impregnation of liquids because of the high permeability and easy breakdown. Furthermore, the rocks have medial to thin layers, easy for painting.
Geological exploration and analysis of the rock material where the paintings exist determined that they were painted over crystalline massive hard, white-greyish rocks and very thick which provide a natural non-permeable character. This rock level localized in the higher part of the Araracuara Formation was a natural canvas for these paintings.
Due to the mineralogical characteristics of the crystalline material, the rock falls off or peels like an onion, showing that these places were reworked to eliminate the surface areas and leave the rock naked and clean.
Another important factor that the ancestral communities took into consideration was geomorphology. They looked for high, steep locations with south-north bearing and difficult access places.
Taking into account that the rock chosen by these communities to place their paintings had more resistant rocks than their surroundings (brittle sandstone), the topographic profile should be more pronounced in these sectors. However, they have inverses slopes to the gradient, avoiding surface drip of water over the paintings.
These features and with the presence of angular quartzite blocks on the base of the paintings shows that they were chosen as cover zones to protect them from the elements. This was evidenced during the field trips and with torrential showers which did not have a direct effect on the paintings.
When the location was ready and prepared as a natural canvas, the other condition was the availability of material for painting. In the areas with quartzite outcroppings and wall paintings, the researchers found violet, white and red colored mineral blotches, similar to those used for the paintings.
They took samples of the paintings and analyzed them using geochemical fluorescence ad X-Ray diffraction. The result was discovering elements such as titanium, iron, and chromium associated with rock silicon. They think these titanium and iron oxides probably ilmenite, anatase, and hematite types come from a washing phase of the rocks of the Mitú Mimagtitic Complex which is the base of the highlands.
The multidisciplinary group of scientists of public and private institutions which participated in the stage of the project (2015-2017), for its appointment as a park had the support of entities such as:
The final result of their work on the Serranía de Chiribiquete is its appointment as a mixed property world heritage site and for the development of future research on our natural parks, currently integrally known.
*The author carried out geological and geomorphological research whose most relevant aspects are presented in this article.
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