Underground landscape

The Hillaire Chamber forms a large space – 30 m wide and 17 m high – and is characterised by tiers of fine grey sediment surrounding a depression produced by subsidence. Several generations of concretions of different shades and morphologies cover the floor. In the south the ceiling, punctuated by pendants, slopes towards the floor. The walls have contrasting appearances: white limestone, red clay, concretions varying from brown to white, grey phosphates due to bats.