Triassic rivers in Rillo de Gallo: current traces from 240 million years ago

Reading an ancient river in stone

The red sandstones of the Triassic, the red rock (rodeno) of Barranco de la Hoz, are the fossilized sands of ancient river systems. Along the trail from Rillo de Gallo to Pardos, these rocks preserve fine details of how the currents moved: small current ripple marks, spoon-shaped and planar cross-bedding formed as sand dunes migrated under water, and the outlines of ancient river channels. Using these clues, geologists have reconstructed how those river networks changed over time.

A complete stratigraphic sequence

Around Rillo de Gallo, more than 600 metres of Permian and Triassic rocks are stacked in order, forming one of the most complete successions in the Iberian Range: from red braided rivers to a shallow sea, and later to coastal salt flats. In the same area lie the fossil forest and the rock art shelters. The Spanish Geological Survey lists it as an official Geosite of Interest.

More to explore

The era of the red rivers is explored in Before us.