Exploring Brazil

Glaciers

Brazil has zero glaciers today. Its tallest peak, Pico da Neblina, tops out at 2,995 m — nowhere near the roughly 5,000 m snowline that keeps the tropical Andes glaciated further west — so no part of the country gets cold enough at altitude to sustain permanent ice. But roughly 300 million years ago, during the Late Paleozoic Ice Age, continental ice sheets buried much of what is now southern Brazil, and their fingerprints are still visible, and still economically useful, today.

Layered varve deposits at the Parque Geológico do Varvito, Itu, São Paulo

Frozen in Layers: the Itu Varvito

At the Parque Geológico do Varvito in Itu, São Paulo, rhythmically banded lake-bed sediments called varves record the annual retreat of that Gondwanan ice sheet: each pale-and-dark couplet is one year's worth of coarse summer meltwater sand layered over fine winter stillwater clay, now preserved as a protected geological heritage site.

Evidence in the Rock

The Paraná Basin's Itararé Group preserves one of the thickest Late Paleozoic glacial records on Earth — roughly 1,300 m of tillite, striated bedrock pavements, and glacial paleovalleys laid down as the ice advanced and retreated across the region between about 360 and 270 million years ago. Striated surfaces near São Bento do Sul, Santa Catarina, even record the direction the ice once flowed: generally toward the northwest.

Impact today: that ancient ice still shapes Brazil's economy and water supply. Reworked glacial outwash sand and gravel now form part of the porous sandstone underlying the Guarani Aquifer System, one of the largest freshwater reserves on Earth, spanning much of south-central Brazil. Slightly later, post-glacial peat swamps filling the same ice-scoured lowlands compacted into the coal seams of the Lower Permian Rio Bonito Formation — still mined today around Criciúma, Santa Catarina, and in Rio Grande do Sul, making Brazil's main coal-mining region a direct legacy of a 300-million-year-old ice age.

Sources & References