Pausanias Description of Greece 8.29.1

[1]
  After crossing the Alpheius you come to what is called Trapezuntian territory and to the ruins of a city Trapezus . On the left, as you go down again from Trapezus to the Alpheius, there is, not far from the river, a place called Bathos (Depth), where they celebrate mysteries every other year to the Great Goddesses. Here there is a spring called Olympias which, during every other year, does not flow, and near the spring rises up fire. The Arcadians say that the fabled battle between giants and gods took place here and not at Pellene in Thrace , and at this spot sacrifices are offered to lightnings, hurricanes and thunders.

[1] After crossing the Alpheios you come to what is called Trapezuntian territory and to the ruins of a city Trapezus. On the left, as you go down again from Trapezus to the Alpheios, there is, not far from the river, a place called Bathos (Depth), where they celebrate mysteries every other year to the Great Goddesses. Here there is a spring called Olympias which, during every other year, does not flow, and near the spring rises up fire. The Arcadians say that the fabled battle between giants and gods took place here and not at Pellene in Thrace, and at this spot sacrifices are offered to lightnings, hurricanes and thunders.