"Mountains?" gasped Billy.
"Yes, and even volcanoes. This has given rise to a supposition that at the pole itself there may be flaming mountains, the warmth of which would have caused an open polar sea to form."
"Nobody knows for certain, then?" asked Frank.
"No, nobody knows for certain," repeated Captain Hazzard, his eyes fixed on the great white wall. "Perhaps we shall find out."
"Perhaps," echoed Frank, quite carried away by the idea.
"What is known about the location of the pole?" asked Billy.
"It is supposed to lie on an immensely high plateau, possibly 20,000 feet above sea level. Shackleton got within a hundred miles of it he believes."
"And then he had to turn back," added Captain Barrington.
"Yes; lack of provisions and the impossibility of traveling quickly after his Manchurian ponies had died compelled him to leave the mystery unsolved. Let us hope it remains for the American flag to be planted at the pole."
"Are there any animals or sea-creatures there, do you know?" inquired the professor, who had been an interested listener.