Yes. The oldest volcano ever found, even today, is Brazilian. “A volcano usually forms in regions where tectonic plates meet. These plates are in the most superficial layer of the Earth, which is always in motion, causing the separation of a few centimeters per year between the continents”, says geologist Caetano Juliani, professor at USP’s Institute of Geosciences. This happened when Brazil was right over an area where plates met, millions of years ago. Today, phew!, we left the danger zone. With the movement of the plates, part of the rocks melts, giving rise to magma, a viscous substance that can reach more than 1,000 ºC. When the magma emerges (along with gases from the interior of the planet), a volcano forms – but the cone walls, which are more resistant, do not melt. Fissure volcanism, on the other hand, rolls when the plates move apart and open the way for a more liquid and less explosive magma. There are still volcanoes with a main crater and other smaller ones. If the magma in the depths runs out, the volcano extinguishes itself and leaves only a few pockets of volcanic rocks – a fact that happened with the Brazilian volcanoes!
SLEEPING GIANT
The Amazon region is home to the oldest volcano ever discovered, around 1.89 billion years old. It is part of a province of volcanic rocks called Uatumã, which spread over Amazonas, Mato Grosso, Pará, Roraima and even Venezuela and Suriname. The original height of the volcano, near the Tapajós River, may have reached 400 meters
IN THE BIGGEST FISSURE
Without much appearance of a volcano, this one was formed 140 million years ago, when the plates moved in opposite directions. At that time, Brazil was almost split in half: a fissure appeared that left Mato Grosso, passed through Paraná and Santa Catarina and arrived in Uruguay. Lava flowed from there and covered an area of 1.2 million km2.
VOLCANIC ARCHIPELAGO
Those who enjoy the beautiful landscapes of the Fernando de Noronha archipelago cannot imagine that, 12 million years ago, that was a group of volcanoes, based at a depth of 4,000 meters. Usually, underwater volcanoes solidify quickly because of the shock with cold water, but the intense volcanism caused the magma to emerge and form the islands and islets
HERITAGE CALIENTE
70 million years ago (almost nothing in geological time), the region where the mining town of Poços de Caldas is located was in full swing. The temperature of 30ºC of the waters there is a legacy of that time. When the volcano was active, lava covered the region and, over time, it solidified and was covered by rocks, which slowly stole heat from the lava.