The Quebrada de las Conchas — Northbound
Ruta Nacional 68 north of Cafayate enters the Quebrada de las Conchas within a few kilometres, crossing the Río Santa María where it joins the Río Calchaquí to form the Río de las Conchas. The canyon takes its name from the fossilised marine shells embedded in the sedimentary walls — evidence that this entire landscape once lay beneath a Cretaceous sea. The rock colours shift as the road progresses: deep reds from iron oxides, pale yellows from the Yacoraite formation, greenish tones where chlorite-bearing sediments were deposited below the waterline of ancient lakes.
The first major stop is Los Castillos — a series of towering red sandstone battlements that rise from the canyon floor in genuine architectural scale, their buttresses and turrets cast in deep morning shadow on the western face. They are the largest formations in the quebrada and the most immediately legible — rock that needs no imaginative effort to read as a castle. A short walk from the roadside pull-over brings the full height into perspective.