migration.

The major towns in the northern Montaña Palentina are: Guardo, a former coal mining town; Aguilar de Campoo, a historic town famous for its biscuit production and Cervera de Pisuerga, a tourist town situated at the beginning of the Ruta de los Pantanos (the Reservoirs Route) and Barruelo de Santullán, which, as the centre of the province's coal mining industry,