The northern and eastern portion of the diocese is mountainous, thickly wooded, and traversed by rivers, among which is the
Ebro, which rises in the mountains and serves as the eastern boundary for
Miranda de Ebro. The
Arlanza which crosses the diocese from east to west flows by
Salas de los Infantes, near the famous monastery of
Santo Domingo de Silos, and through the center of the well-known town of
Lerma. The mountainous region is unproductive of cereals, but fruits grow in abundance, and fine pasture-lands sustain great herds of cows and sheep, which furnish excellent meat and milk. Delicate cheeses which take their name from the city and are famous throughout Spain, are made in this section. Minerals are abundant, especially sulphate of soda, common salt, iron, and hard coal. The southern part of the diocese, especially the valley and plains, is fertile and produces abundantly vegetables, cereals, and quite a quantity of wind. The climate, cold but healthy, is damp towards the north. Although this section has few industries, the transportation of its fruit and minerals is greatly facilitated by the numerous highways and by the railroad between
Madrid and
France which crosses the eastern side of the diocese from south to north. There are also some secondary railway lines for the operation of the mines. == History ==