Access the Inaccessible: Exploration of the Dent de Crolles (Isère, France)

When Fernand Petzl found the solution! No life is without dreams, without goals to reach... No matter who we are, there is always the "inaccessible" waiting. To reach it, we prepare, work out our moves and our solutions, and finally we succeed at going beyond what we ever thought possible. This path belongs to all verticality enthusiasts. It is the path that the artisan, creator, and caver Fernand Petzl took in the 1930s to explore the caves of the Dent de Crolles and to invent the tools he needed. The beginning of an adventure that would later be called Petzl.

Trou du Glaz - Guiers Mort, an inaccessible link?

Isère, 1930. Fernand Petzl was barely twenty years old. Living in Isère at the foot of the Chartreuse, the young man was an artisan modeler. In his spare time, Fernand had one passion: caving. From the early 1930s, he engaged in this activity with his brother, above their home, in the caves of the Dent de Crolles. The Dent de Crolles that would become the secret garden in which he would achieve his quest of the inaccessible.

In the middle of that decade, Fernand threw himself into the challenge of linking the Trou du Glaz, on the west face, with the Guiers Mort, a cave located 400 meters below. He knew that the two were connected. Early on, he teamed up with another caver, Pierre Chevalier, who was on the same project. And a dynamic duo was born.

A climbing mast for the unattainable

At the beginning of the Second World War, the explorers discovered 3000 meters of caves, bringing the total network to 5500 meters. To succeed, the two men spent some time in Fernand's workshop in Saint-Nazaire-les-Eymes, creating the tools they needed. One of these would turn out to be key: the climbing mast created in 1940. 

"To reach the top of a seven-meter high, impossible-to-climb wall, Fernand built a portable 'climbing mast' that Pierre had designed. During this period of scarce resources, Fernand succeeded in designing the low-cost, 25-meter apparatus by using pieces of furnace piping that could be connected to each other. Guy-wires stabilized the structure and served as ladder attachments. The entire system weighed no less than 30 kilos and had to be moved through tight, dark spaces. It was definitely worth the effort, as the mast proved vital on more than one occasion: for ascending steep sections, descending shafts or even for crossing gaps."

Slowly but surely, Fernand, Pierre and their friends progressed. The link was completed in 1941.

More tools

After this feat, they continued exploring the network of the Dent de Crolles until 1947. During these years, the creativity of the two explorers was always evident. "For the tallest shafts, Fernand designed a wooden platform that could serve as an anchor for setting up the climbing mast. He also tested a few other tools of his own design, most notably hooks to ascend a knotted rope, similar to those that roofers were already using at the time."

Pierre Chevalier, an engineer at Rhône-Poulenc, designed a rope for himself using a new material: nylon. "The first nylon ropes were as stiff as cables and pricked his hands, but after some experimenting, the manufacturer finally found the right fiber thickness. This marked the beginning of the end for hemp ropes, which absorbed water and broke easily."

Twelve years after their first outings, the network that Fernand, Pierre and their friends had brought into the light was now 603 meters deep, and one could cross the Dent de Crolles four different ways, through 17 kilometers of caves and shafts. The solutions they employed, like the climbing mast and the nylon rope, lasted a long time, and in fact still exist today. For some, they have radically transformed the practice. They result from a spirit of practicality, cleverness and innovation. A spirit that, more than sixty years later, means a great deal to Petzl.

Quotes are sourced from the book, From the Deep: The Petzl Adventure, Éditions Guérin, 2012