South of the Ebro the ground changes: this is the Sistema Ibérico, not the Pyrenees — a country of limestone and spring-fed ravines where the Piedra and the Mesa cut down toward the Jalón above Calatayud. The Monasterio de Piedra makes the character plain: travertine, cold springs, water that comes out of the rock clean and stays cool where it is shaded. There is genuine small-stream trout interest in the higher, spring-influenced reaches, but it is scouting water rather than a destination — flows are seasonal, access is patchy, and the warmer lower reaches turn over to barbel and chub. Go with light tackle, modest expectations, and an eye for the cool, shaded corners.
- Limestone