They are foothills of the highest peak in Provence, Mont Ventoux, which is situated just to the east. The dramatically jagged shape of their peaks was formed by horizontal strata of Jurassic limestone being folded and forced into a nearly upright position and subsequently eroded into sharp-edged ridges and spikes. The highest peak of the Dentelles is St-Amand, at 734 m (2,400 ft). The range, which is about 8 km wide, offers over 600 trails for walking, rock climbing, and mountain biking. The foot of the Dentelles is surrounded by vineyards of the Rhône Valley.