Conglomerate, close-up. Also called pudding stone, this rock type is made of old coarse river deposits such as quartz pebbles, gravels and, sometimes, silicified wood, all cemented together by hardened sand. This specimen dates from the Oligocene (35 million years ago). Resistant to wear, and easy to cut, this rock type was used to make millstones. This specimen is part of the Geoscope geological park, located between Les Monts-Vert and Albaret-Sainte-Marie, central France.