The Guiana massif, also known as the “Guiana Shield,” is a geographic region located in the northeastern part of South America. It covers the entire territory of the countries Guyana, Suriname and French Guiana, and part of the territory of Venezuela (Amazonas, Bolívar and part of Delta Amacuro states), Brazil (small areas of the north) and Colombia, with an approximate area of 1,520.000 square kilometers.
As for its delimitations, it is found to the east with the Atlantic Ocean, to the north and west with the Orinoco River, to the southwest with the Negro River belonging to the Amazon, and to the south with the Amazon River.
The United Nations Development Program has described the Guiana Shield as an area of great significance at a regional and global level, since it is home to a great variety of ecosystems, key species of biodiversity, and represents 25 % of the world's forests. In addition, it contains 20% of the planet's fresh water.
The best known references of the Guiana massif are:
-El Salto Angel, the highest waterfall in the world with a total height of 979 meters.
-The tepuis, a group of plateaus made up of rocks, with a particularly high height, and which constitute one of the oldest formations on earth.
Both are in the territory of the massif belonging to Venezuela.
Formation of the Guiana massif
According to Otto Huber, an Italian ecologist who has focused his work on Venezuelan Guiana, the territory that today makes up the Guiana massif was formed around 4,000 billion years ago in the Precambrian era, the first and longest historical stage of the Land.
At that time, during the time of cooling of the Earth, a series of solid earth cores formed that were forming the earth's crust, and that later flourished in what we know today as continents.
One of those first nuclei was generated on the territory where the Guiana shield is today.
These original surfaces (the previously mentioned nuclei), which were also never under the sea, are the surfaces that we have today on the flat tops of the tepuis.
Their altitude –which reaches 2,810 meters above sea level- is due to the fact that since their formation, and for millions of years, the original lands of the earth have been experiencing vertical tectonic uplift movements, without undergoing folding and with little orogenic activity.
The name "shield" is used in geology to designate precisely the continental regions composed of rocks formed in this period, and that were never covered by the sea. Hence, the massif is also called the "Guiana Shield".
Geography
Within the shield are vast areas of savannas, such as the complex made up of the Venezuelan Gran Sabana in eastern Bolívar state, the Rupununi Savannah in southwest Guyana, and the Roraima Savannah in northern Brazil.
In many of these savannas, under the sand is a rigid layer of clay, resistant to penetration by tree roots.
In addition, in the heavy rainy season, some savannas tend to flood. For both reasons, the growth of forests in these spaces is limited.
In addition, mangroves, lowlands with numerous rivers, seasonally floating tropical savannas, coastal swamps, jungles and isolated mountain ranges can also be found in the massif area; each of them with its specific type of vegetation.
With the exception of some populated centers, such as Puerto Ayacucho, Ciudad Guayana and Ciudad Bolívar, most of the massif is very sparsely populated and with limited access, which, although it has benefited the natural maintenance of the area, has made it difficult to explore and study.
Weather
Overall, the climate of the Guiana Shield region is tropical, and varies depending on the altitude of the area and the effects of the trade winds on rainfall patterns.
In parts that are at sea level, such as French Guiana, Guyana, Suriname and the Venezuelan Bolívar state, the annual average temperature is 25 ° C.
However, in the jungle parts the climate is more humid and rainy, as in the Venezuelan state of Amazonas and Brazil, and can reach 15 ° C in the coldest months.
On the other hand, in this region there are only two seasons, one for rain and the other for drought. In some areas, there are up to two rainy seasons throughout the year: one of intense rains between May and August, and a second shorter and less intense season between December and January.
Biodiversity
One of the most notorious features of the Guiana Shield is the biodiversity existing in its territory, since it contains a significant percentage of species in relation to world biodiversity.
A compilation made by the Guiana Shield Biological Diversity Program estimated that there are between 13,500 and 15,000 species of vascular plants in this area, which represents 5% of the estimated world total.
Furthermore, some authors believe that 40% of the plant species found in the Shield are endemic, that is, they do not exist anywhere else outside of it, which represents about 6,000 species.
The number of birds present in this area is also significant: 10% of the total known species worldwide (1,004 species out of 10,000).
On the other hand, in the area there are 282 types of mammals out of a total of approximately 4,600 (6%), 269 types of amphibians out of a total of 5,000 (5.5%) and 295 types of reptiles out of a total of 8,100 (3, 6%).
Even so, there are still unexplored areas of the shield, such as the top of some tepuis, and parts located in Brazil and Colombia.
Means
The natural resources most commonly found throughout the region are diamond, bauxite, gold, oil, wood, aluminum, and iron.
The extractive activity of these resources is one of the economic activities carried out in these territories, together with agriculture and livestock, which is carried out to a greater extent.
However, currently there is a significant problem of illegal exploitation of these resources, which occurs due to the little government control that countries exercise over these areas.
The way in which illegal groups exploit these resources has caused negative effects on the environment such as:
-Deforestation
-The contamination of soils and rivers.
Noteworthy is the misuse of mercury for illegal extraction - which reduces the capacity to support life in the environment, putting the indigenous indigenous groups of the region at risk due to the occupation of these guerrilla and criminal groups in the area, among others.
Due to all of the above, various specialists have demanded that more resources be invested in monitoring and protecting these areas, since they are vital for the planet's general eco-system.
References
- UN News Agency (2014). The Guiana Shield does not have any insects. Consulted on September 6, 2017 on the World Wide Web: unperiodico.unal.edu.co.
- HOLLOWELL, T. & REYNOLDS, R. (2005). Checklist of the terrestrial vertebrates of the Guiana Shield. Accessed September 6, 2017 on the World Wide Web: academia.edu.
- THOMPSON, A. (2016). The Guiana Shield, 'The Green House of the World'. Retrieved September 6, 2017 from the World Wide Web: news.mongabay.com.
- Wikipedia, The Free Encyclopedia. Retrieved September 6, 2017 from the World Wide Web: Wikipedia.org.