I declare that it is the amount of the sulphur which is the cause of the fire that is constantly burning, and this is how it is: When the fire begins to perform an action in the veins of sulphur beneath the earth it continues always to burn the sulphur and the earth before it, so that it cannot be extinguished.
Consequently it makes holes and crevices before it in the earth, and when the sulphur that is naturally in it comes to the end, it grows again. When it grows, it turns again and burns it again, and that growth of the sulphur and the burning of the fire are ever increasing, and the flame as it rises from it, throws up many balls and masses of fire which come forth from the substance of the sulphur, and they collect in one direction and mountains are formed from them.
There is often heard a great, terrible sound from the wind going into those hollows and blowing with the flame as it comes out. The waters that are generated from these fiery places are hot, for as I have mentioned, the waters receive their accident from the place whence they come.