Grand Crêt, Mountain summit in Lélex, France.

Grand Crêt is a summit of pale, mostly snow-covered limestone in the Jura range, in the Ain department. Its broad rounded ridge runs nearly horizontal, rising gently to the right, with darker rock exposed along the crest and dark conifers scattered in bands across the lower and middle slopes. The summit lies on the axis of the Monts Jura anticline, between two parallel faults visible at the base of the east and west flank cliffs.

The summit consists of Upper Kimmeridgian limestone with flint and a lithographic facies. It lies on the axis of the Monts Jura anticline, between two parallel axial faults visible at the base of the east and west flank cliffs. These faults predate the transverse fault networks of the Montoisey and Crêt de la Neige, which offset them.

The summit stands in the Réserve naturelle nationale de la Haute Chaîne du Jura and the Parc naturel régional du Haut-Jura. The reserve's name refers to the high chain of the Jura, the easternmost and highest range of the French Jura, which the Grand Crêt tops at 1,702 m. Hikers reach it on the GR Balcon du Léman along the crest from the Crêt de la Neige or the Montoisey.

Visitors can access the summit via hiking trails that depart from nearby villages like Lélex. The most enjoyable season is during warmer months when the paths are fully open and weather conditions are favorable.

The Grand Crêt is separated from the Crêt de la Neige by a saddle whose lowest point lies at about 1,670 m, which is why it is often not counted as an independent mountain. Two parallel faults following the anticline axis can be traced in the landscape at the base of the summit cliffs on both the eastern and western flanks.