The Oncala mountain pass Nature · Oncala, Tierras Altas, Soria Image of Oncala, not of the place itself. At 1,454 metres of altitude, this saddle between the Sierra de Alba and that of San Miguel is the gateway to the Tierras Altas and the place where the river Linares rises; by it the flocks climbed on their way to the winter pastures. Photo: www.pmrmaeyaert.com (CC BY-SA 3.0) What to see and do in Oncala