Volcanic rocks and erosion, the (geo)history of Iguazu Falls, Brazil

Well, here goes a very last minute decision to travel to Brazil. With < 2 weeks to go I decided to join up with my sister (who is a video blogger and recorded out trip, http://www.heynadine.com) and her two friends (for the 1^st part) and go travel for 3 weeks in Brazil. Now, Brazil is a huge country (mind you, not as big as Canada…) but that mean lots of flying is required. We got an air pass with destinations to: Sao Paulo – Iguazu Falls – Manaus (Amazon) – Salvador – Rio.

The renowned natural beauty, exotic ecosystems and diverse culture of Brazil makes it a challenging but rewarding destination. We started off in Sao Paulo with only a day and a bit to explore some of the historical centre, the central park, and a cool graffiti alley called Batman’s Alley. After that we took a late flight out to see one of the new 7 wonders of the world (which I was told was a must-see if visiting Brazil). Therefore I’ll start off this blog off with this location, and one of the most spectacular sights I’ve ever seen in my life, Iguazu Falls.

Rock floods and water falls

There are over 275 individual falls at Iguazu, and these can be attributed to the rocks they are sitting on. About 135 million years ago a massive volcanic eruption flooded the area with basaltic lava (like the high velocity, low viscosity pahoehoe lava currently forming Hawaii). This lava covered a former desert that was present in the region, and there were several stages to the lava flow. Therefore, this inter layering of basalt with minor sandstone formed the basis of Iguazu Falls. The region has been subjected to various faults; cracks within the earth’s surface (due to moving tectonic plates, usually causing earthquakes). The actual waterfalls only formed recently (geologically speaking, so <20,000 years) from flowing water from the Iguazu River that utilized these natural breaks and weaknesses within the bedrock. And vol-la! The waterfalls were formed.

Like most waterfalls (Niagara, for example), Iguazu is retreating due to the erosion of the water on the basalt landscape. The original location of the falls was actually 28 km downstream from present day, and these falls will keep on moving farther and farther back as time goes on.

Final Thoughts

Seeing impressive, massive waterfalls is one thing… but to stick it in the middle of a sub-tropical rainforest and have over 275 individual waterfalls is something only Iguazu has. I would definitely recommend making a stop over here if ever in Brazil, and spend 2 days rather than trying to cram both the Brazil and Argentina side in one day (like some people did… i.e., me). The falls undeniably earn their place as one of the 7 Wonders of the World and are a sight not soon forgotten. Next stop, the Amazon…

-Stephanie

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