At Lascaux, a great many lamps have been discovered, most of them in the lowest parts of the cave where the concentrations of CO2 are highest. The higher the concentration, the lower the flame in the lamp; at a level of 3% of CO2, the flame is extinguished. Even if it is difficult to determine the exact concentration of CO2 at the time the cave was decorated, it is highly likely that this phenomenon explains the large number of lamps found in the lower areas, particularly at the foot of the Panel of the Great Black Cow.