The mountains lend their name to the Apennine peninsula that forms the major part of Italy. They are mostly verdant, although one side of the highest peak, Corno Grande, is partially covered by Calderone glacier, the only glacier in the Apennines. The eastern slopes down to the Adriatic Sea are steep, while the western slopes form foothills on which most of peninsular Italy's cities are located. The mountains tend to be named from the province or provinces in which they are located; for example, the Ligurian Apennines are in Liguria. As the provincial borders have not always been stable, this practice has resulted in some confusion about exactly where the montane borders are.