To the west of Balaguer, the capital of La Noguera, a row of small hills (the Serra Llarga) forms a barrier between the Catalan Central Depression and the Pre-Pyrenees, the location of significant gypsum deposits. A mosaic landscape of scrubland, thyme and dry meadows with dryland crops that almost completely cover the southern part of the area. This environment is a good habitat for steppe birds, with the largest populations in Catalonia of some key species.