What visible remains of Fontveille Adit 3 can you observe on site?

Visitors can identify two primary terrain anomalies: the 'razzier' (an artificial slope of discarded waste rock covered in moss) and a circular collapse depression that marks the precise underground axis where the adit entered the mountainside.

Why is the entrance to Fontveille Adit 3 no longer visible?

The portal was sealed during the 1997 safety campaign across the Matheysine coalfield: steel support arches were removed, the surface workshop was leveled, and the entrance was heavily blasted and backfilled with earth to eliminate cave-in hazards.

Can you enter the underground tunnels of Adit 3?

No, subterranean access is completely non-existent. The tunnel mouth and initial meters have been completely collapsed, sealed, and buried beneath several meters of compacted fill.

What was the role of Adit 3 compared to other drifts in Fontveille?

Adit 3 was positioned at the highest elevation of the Fontveille mining sector, sitting above Adits 1 and 2 to exploit the upper layers of the anthracite coal seam directly from the steep slope.

Fontveille Adit 3 – Patrimoine du Dauphiné

Fontveille Adit 3

Perched at the very top of the wooded Fontveille hillside, Adit 3 is a true ghost site. While the forest has reclaimed the area and concealed the old anthracite mining infrastructure, the landscape still holds telltale clues left behind by the miners. Follow this guide to read the subtle traces hidden in the terrain.

Quick Facts

Feature	Details
Site Name	Fontveille Adit 3 (Galerie 3 de Fontveille)
Location	Fontveille, Susville (La Mure Coal Basin / Matheysine, Isère, France)
Type of Heritage	Former anthracite coal extraction adit
Position	Highest level of the Fontveille mining complex
Visible Remains	Waste rock pile (« razzier »), circular collapse depression
Original Structures	Steel support arches, foundations of a small service building
Reclamation Work	1997 (demolition, massive backfilling, and slope grading)
Current Condition	Adit portal fully sealed and buried beneath thick backfill
Access & Safety	Off-trail, rugged mountain terrain. Underground access is strictly non-existent

1. The Crown of the Fontveille Workings

Look toward the upper slopes above you. This steep, quiet forest was once an active industrial hub:

The highest opening: Among all the mine entrances dug into the Fontveille slope, Adit 3 occupied the highest elevation to reach the upper layers of anthracite.
A transformed landscape: Decades ago, this hillside echoed with the noise of miners, carts, and equipment. Today, the industrial hustle has faded, leaving behind an undisturbed mountain setting.

2. Spotting the Clues in the Woods

At first glance, nothing seems to indicate that an extraction drift ever existed here. You will not find an open portal or stone archway. Instead, two ground anomalies reveal the site’s industrial past:

The « razzier » (waste rock dump): Just below the old portal along the slope lies an artificial scree pile. Known locally as a razzier, this heap consists of barren rock discarded during digging. Although moss and trees now cover it, its distinct slope and broken stone still prove the immense volume of rock moved by hand.
The collapse depression: Slightly higher up, a round hollow indents the forest floor. This funnel formed when the first few meters of the buried tunnel crown gave way under the weight of the mountain. It pinpoints the exact underground trajectory taken by the miners.

3. 1997: The Final Erasure

Why is the tunnel opening completely invisible today?

What stood before 1997: Up until the late 1990s, the entrance was still clearly identifiable. Steel support arches framed the portal opening, flanked by the stone remains of a small service shack used by the crew.
The regional safety initiative: In 1997, a major safety campaign sealed old mining concessions throughout the Matheysine region to prevent cave-ins and illegal entry. Workers removed the steel framing, leveled the service building, and collapsed the mouth of the drift.
Return to nature: Bulldozers spread deep layers of earth over the platform, re-grading the slope to match the mountain’s natural contour. The mine was permanently locked away underground.

Tips Before You Go

Tread carefully: The hillside is steep, uneven, and off marked walking paths. Watch your step around the loose stones of the rock dump.
Stay safe: The underground workings are completely blasted and backfilled; there is zero underground access. Enjoy exploring the surface history!

Only in French