Following the line marking the division of the waters that flow into the Po from those that feed the Rhone or the Rhine, the main ridge of the Lepontine Alps describes a somewhat irregular curve, convex to the north, from the Simplon Pass to the Splugen Pass. With the single exception of the Monte Leone, overlooking the pass of the Simplon, the summits of this portion of the chain are much inferior in height to those of the neighbouring chains; but two peaks of the Adula group, culminating at the Rheinwaldhorn, exceed in height.