The Unforeseeable Future of Brazil’s Hidden Gem

Chapada Diamantina’s tropical semi-humid, semi-arid landscape is home to karst topography containing underground rivers, systems of quartzite caves, mesas and rock formations bordering valleys, and majestic waterfalls spilling into crystal clear lakes. Such geographical features were crafted through millennia of folding, weathering and erosion.

Chapada Diamantina Karst Topography Created Through Weathering & Erosion

Using cross-cutting for strata depicts years of chemical weathering and erosion of rock by both oceanic and fresh-water river systems. Anticline folds shifted and shaped the aboveground anticlinal valleys. Subterranean groundwater and streams dissolved and continue to eat-away at sedimentary rock carving karst underground structures including caves and caverns. These processes continue to be a force in Chapada Diamantina’s landscape.

Chapada Diamantina Anticlinal Valley Created Through Folds

Chapada Diamantina 10,000 Years in the Future…

In ten thousand years Brazil’s Chapada Diamantina will be approximately 1km west of its current location. The South American Plate moves roughly 10cm west every year while the Nazca Plate moves about 16cm east each year. The South American and Nazca plates interact with a closing velocity of nearly 26cm per year. This phenomenon increases tectonic activity along the coast of South America. Although these tectonic plate movements seem significant, not much will be different in 10,000 years except Chapada Diamantina’s new GPS coordinates. Chapada Diamantina will sit less than a mile west than it does it today, resulting in much of the same annual rainfall and climatic patterns.

South American & Nazca Plate Movement

In 1,000,000 Years…

In one million years Chapada Diamantina will potentially experience more rainfall, slightly lower temperatures and more seismic activity. By this time period the South American plate will be 100km west and the Nazca Plate will be 16km east from current measure. Chapada Diamantina’s new location will be much more inland and receive about twice as much annual rainfall than currently recorded. In one million years this convergent boundary will produce many more earthquakes and volcanic eruptions. Volcanic eruptions contribute to the Haze Effect, which basically lowers average global temperatures. This seismic activity will alter Chapada Diamantina’s current climate and produce slightly cooler temperatures.

Brazil's Average Annual Rainfall

 

The Haze Effect from Volcanic Eruptions

100,000,000 Years Later…

One-hundred million years from now Chapada Diamantina will change to a completely tropical landscape covered in island-like trees and sandy beaches. The South American Plate will be 10,000km west of current measure and Chapada Diamantina will have moved to what is now the South Pacific Ocean, just a few km south of Fatu Hiva of the Marquesas Islands. The elevation will be much lower and become a victim to the rising sea level. The divergent plate boundary from the South American Plate and African plate will have increased and created volcanic islands along the wider Mid-Atlantic Ridge. The African Plate moves 3.75cm east each year and in one-hundred million years it will be 3,750km east while the South American Plate is 10,000km west. Chapada Diamantina’s entire landscape and climate will be completely altered in 100,000,000 years.

South American & African Plate Divergence Along South Atlantic Ridge

 

Fatu Hiva in South Pacific Ocean

Chapada Diamantina’s landscape and climate will be completely different but equally as beautiful when weathering, erosion, and tectonic activity reshape its appearance. Nonetheless, Brazil’s hidden gem will remain an icon and a place to witness the features Earth’s geographical processes left behind.

Chapada Diamantina at Sunset

References:
http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html
http://blank005.tripod.com/geology/tectonics.html
http://www.geo.mtu.edu/~hnlechne/volcanichazards.html
http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry29.html

Weather & Climate

Chapada Diamantina is located within the Brazilian state of Bahia and just 283 kilometers from the coast in Salvador. 

Chapada Diamantina located in the Eastern Brazilian state of Bahia

This region is particularly known for experiencing the effects of surface winds during the summer (austral) months in the southern hemisphere. These equatorial surface winds occur within the Intertropical Convergence Zone or ITCZ. The ITCZ is a band of low pressure circling the equator and is associated with strong rainfall.

Link to Intertropical Convergence Zone Graphic

Seasons in Southern vs. Northern Hemispheres

The Third Law of Geography states that air always flows from high pressure to low pressure. In the southern hemisphere during December, January, and February the low pressurized Intertropical Convergence Zone is pulled south and brings intense rainfall to Chapada Diamantina. The northern hemisphere’s summer (boreal) months of June, July, and August causes the ITCZ to travel north depriving Chapada Diamantina of rainfall.

ITCZ effects during Northern Hemisphere Boreal months vs. Southern Hemisphere Austral months

Rainfall changes drastically based on which direction the ITCZ is being pulled

The warm air in the Trade Winds flow towards the low pressure in the Intertropical Convergence Zone and are responsible for many of the weather patterns linked to this region. Trade Winds blow westward above and below the equator. This combination causes upward winds as they are heated resulting in a calm area known as doldrums.

Trade Winds converging above and below the equator as warm air rises producing clouds and rain

Trade Winds are viable assets to ocean circulation near Chapada Diamantina in Brazil. They drive the South Equatorial Current (SEC) and once the current approaches Brazil it splits into both the Brazil and North Brazil currents. This mix of major warm currents derives and produces giant subtropical Gyres. Gyres are large circular ocean currents driven by subtropical high pressure.

Major warm currents forming giant subtropical gyres

Finally, every seven years or so pressure flip-flops and the result is severe drought in Chapada Diamantina as well as other regions in Brazil. This is due to El Niño Southern Oscillation (ENSO). El Niño effects are felt globally.

El Nino effects across the globe

References:

http://www.skepticalscience.com/print.php?n=740

http://www.pura-aventura.com/blog/chapada-diamantina-climate/

http://gosouthamerica.about.com/od/braregnortheast/p/ChapadaDiamant.htm

http://kids.earth.nasa.gov/archive/nino/global.html

Folding, Weathering & Erosion

Chapada Diamantina contains breathtaking views shaped from folding. The national park is also the outcome of ancient weathering and erosion, resulting in beautiful features.

A Chapada Diamantina view made possible through folding processes

Folding is always the result of compression stresses and once a fold is eroded there are unique landforms created. Chapada Diamantina expresses an anticline fold within the rock groups of the Paraguaçu region. Once the anticline fold eroded over time, an anticlinal valley was produced.

Chapada Diamantina's Anticlinal Valley, Pai Inacio, is the result of an anticline fold erosion

The Paraguaçu region within Chapada Diamantina consists of sandstones, siltstones, and argillites. These rocks are much softer, allowing them to be vulnerable to weathering and folding. The folds in the Paraguaçu region allow water to easily enter the rock’s structure, which results in the erosion of these rocks.

Rock types (sandstones, siltstones, and argillites) within Chapada Diamantina's Paraguacu region

Ancient rivers and oceanic currents are responsible for the weathering as well as erosion of the rocks at Chapada Diamantina. Dating the rocks shows that Chapada Diamantina ages back to Pangaea. The national park is an ancient site, which has been broken down and shaped through weathering and erosion. Weathering refers to the breaking down of rock whereas erosion indicates the transport of weathered material.

Chapada Diamantina's, Canyon do Buracao, depicts the weathering and erosion that has crafted a majestic scenery

The rocks in Chapada Diamantina’s Paraguaçu region are rich with minerals, allowing a chemical decay process to occur. The chemical decay process is understood as the chemical alteration or decomposition of rocks and minerals. The sandstones, siltstones, and argillites are chemically decayed through dissolution as well as chelation and biological organic acids. Through dissolution minerals in the rocks are completely dissolved by water. Epilithic, or rock surface, organisms such as mosses alter and decompose the mineral rich rocks at Chapada Diamantina through chelation.

Fumacinha Fall surrounded by weathered rock created through dissolution and chelation processes, depicted by grooves in the rock walls and mosses atop rock surface

Overall, Chapada Diamantina’s Paraguaçu region was made possible by folds created from compression stresses as well as through weathering and erosion. The results of such processes are anticlinal valleys like Pai Inácio and beautiful scenery such as Fumacinha Fall and Buracao Fall.

Buracao Fall portrays evidence for weathering and erosion of mineral rich rock such as sandstone

References

http://gosouthamerica.about.com/od/braregnortheast/p/ChapadaDiamant.htm

http://www.atlasofwonders.com/2011/11/chapada-diamantina.html

http://www.biosferabrasil.com/meu_destino.php?cod_destino=4&idioma=i