Underground Clermont-Ferrand are dug in the tuff. The tuff is consolidated volcanic ash, easy to dig. Sometimes you may discover metamorphic rock inside the tuff. This is this kind of rock you can see on the left of the photo. Useless and too heavy, it was left in the underground.

The limestone quarry of Chanaz is a smaller operating on three levels. The ceiling height is between 5 and 10m. Sometimes, holes in the floor let you see underground levels.

The network size is almost 4km developed. It was exploited from 1860 to the end of the Second World War to make cement. Portions was reused as mushroom farm thereafter (row crops and cultures in bags).

In this photo taken at the highest level, we see the intermediate level, row crop bottom right and even two holes overlooking the lower level. This is the most impressive part of the network with large volumes!

The quarry of Annet on Marne is called "Purpled". The all quarry is in bad shape. Ceils are down on many places. See this pillar who does not support the ceil anymore...

One of the cameras of Staff of the Navy. We see any effectiveness.

You can't see it, but there is a little stairs on the right, on the roof.

If you look closely, you can see a security guard on the picture.

A panoramical and spherical view inside the Herblay quarry. Use the mouse, click and move to see the ceiling!

This well was the only access to other parts of the quarry. Here, explorers sure to be the only ones in the quarry let the rope that we see. After they know about us. They came to retrieve the rope. Ridicule does not kill. In short, we had to dig the stone steps to the next time. In the end, it was more practical to have a permanent ladder!

In the first series of work, caretaking had significantly increased, following numerous visits from people not covert. They finally opted to remove the tarps. Thus, the guards could easily see people climbing. This photo was taken the day before the parade of July 14, 2006. The lack of cover in no way hampered the ascent to the summit.

Open your mouth and close your eyes. You'll see, it gets better.