Brazil 2012 Fieldwork Diary: Entry 12

Brazil 2012 Fieldwork Diary Entry 12: Cachaça on the Rocks

A 50 litre can of cachaça at the distillery we visited. Photo by Ken Angielczyk.


I almost feel guilty about the pun in the title of this entry, but it does capture two of the important things we did today. Since it's a science blog, I'll start with the science side of things.
We traveled back to Teresina from Nova Iorque today. A little more than halfway between the two cities is the town of Amarante, and just outside of Amarante are some rock exposures we visited last year. The exposures are supposed to contain the contact between the Pedra de Fogo Formation and the older Piauí Formation that underlies it. The Piauí Formation is thought to have formed in a marine environment, and the contact between the formations is not well exposed near Nova Iorque, so we thought this would be a good place for Roger to see it and fill in his knowledge about the oldest rocks of the Pedra De Fogo Formation. The exposure of interest is located close to the road to Teresina, but somewhat below it, so we had to climb down and then work our way back up the exposure, studying the rocks as we went.


Hiking down to the Piauí Formation near Amarante. Photo by Ken Angielczyk.


The surprising thing is that the rocks did not seem to have a strong marine character to them. Instead, the appeared rather similar to rocks we were seeing in the Pedra de Fogo Formation. For example, some of the features of the bedding (or layering of the rocks) and the presence of small, round grains called ooids are consistent with the rocks having been formed in a shallow lake or near the edge of a seaway. There were also somewhat more terrestrial rocks present, including ones with mineral crusts called rhizocretions that form around plant roots in certain soil types. At the top of the hill, near the level of the road, are rocks that represent sand dunes similar to the ones we saw near the top of the Pedra de Fogo Formation near Pastos Bons, even though these are supposed to be near the bottom of the formation in the area near Amarante. Different interpretations of these observations are possible. One is that the rocks are mapped incorrectly in this area. In other words, previous geologists might have mistakenly assigned rocks belonging to the Pedra de Fogo Formation to the Piauí Formation. Alternatively, if at least some of the rocks belonging to the Piauí Formation represent sand dunes and shallow water environments located in their vicinity, this could mean the this general style of environment persisted in the Parnaíba Basin for some time. Indeed, even the Motuca Formation, which overlies the Pedra de Fogo, seems to have been largely formed by sand dunes. In that case, the Pedra de Fogo Formation would capture a snapshot of the animals and plants living in these environments. At the moment, I think I support this interpretation, given that the Parnaíba Basin was located near central Pangaea at the time, and desert environments are expected to have been present in the subtropical portions of such a large continental landmass. The Pedra de Fogo Formation might include more fossils than the Piauí or Motuca formations because it happened to be deposited at a time when conditions were slightly wetter or sea level was a bit higher resulting in the assemblage of animals dominated by fish and amphibians.


Besides the outcrops of the Piauí Formation, another thing that is conveniently located close to Amarante is the distillery for Cachaça Lira. Cachaça is a spirit distilled from fermented sugarcane juice that is very popular in Brazil. It's sometimes compared to rum, but differs from the latter in that fresh sugarcane juice is fermented to make cachaça, whereas molasses is usually the starting point for rum. The Cachaça Lira distillery is still run by descendants of the man who started it in the late 1880's, and is extremely picturesque. The family is very welcoming, and it's a wonderful place to stop on a hot afternoon to chat, eat fresh carambola (star fruit) from the tree in the garden, and have a sip of cachaça.


Where the magic happens: the Cachaça Lira distillery. Photo by Ken Angielczyk.


 

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