He made the first ascent of La Meije (Massif des Écrins) on 16 August 1877 with his son and Emmanuel Boileau de Castelnau.

He was a shepherd, who spent each summer with the sheep on the long trip to the Alpine pastures in the Vénéon valley in the Dauphiné.

He became familiar with the entire upper part of the valley surrounding Vénéon, from Olan and Les Bans on the south to Ailefroide and Barre des Écrins in the east to La Meije in the north.

With Boileau de Castelnau, Gaspard formed one of the most brilliant ropes of their era, making a dozen first ascents in the 1876 and 1877 seasons.

[5][6][7] On 4 August 1877, Boileau de Castelnau and Gaspard tried a new ascent of the Meije by the south side, a route attempted the previous year by Henry Duhamel.

The descent was even more challenging than the ascent, and they were obliged to bivouac on the night of August 16 on an uncomfortable ledge, but managed to return to La Grave the following day.

Quiet, even phlegmatic, he was a good rope partner and camping companion: he could discuss any topic, and his wit and sophisticated sense of humor have passed into legend.

He left 15 children, including six sons (Maximin, Pierre, Casimir, Joseph, Alexandre, Devouassoud), who were also mountain guides.