Serra Geral Formation, Geological formation in South America, Argentina and Brazil.
The Serra Geral Formation is a geological structure in southern Brazil and northern Argentina made up of thick layers of basaltic rock. The rock sits in horizontal bands that are clearly visible along canyon walls, cliffs, and flat-topped hills across the region.
The formation was built up around 130 million years ago when enormous lava flows covered the land in repeated eruptions over a long period. This episode is considered one of the largest volcanic events in Earth's history and left behind one of the thickest basalt sequences known.
The dark red soil that forms over the basaltic rock is a familiar sight across southern Brazil and northern Argentina, where farmers have long adapted their crops to its properties. This soil, known locally as terra roxa, gives the landscape a color that locals recognize as a sign of fertile ground.
The rock layers are accessible at several points in southern Brazil and northern Argentina, including inside national parks and along river canyons. Visitors who want to see the outcrops up close should wear sturdy shoes, as the ground can be uneven and the paths near canyon edges are steep.
Within some parts of the basalt sequence, sandstone lenses were trapped between lava flows before the rock hardened, preserving traces of animals that lived in the area around 130 million years ago. These pockets of sediment inside a volcanic formation are rare and give scientists a window into the wildlife of that distant period.
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