What does Rutherford find out about "a cone-shaped" mountain as high as the highest of the Himalayas? (Epilogue)

From the text:

Then I asked if he had ever heard of a cone-shaped mountain almost as high as the highest of the Himalayas, and his answer to that was rather intriguing. There was a legend, he said, about such a mountain, but he thought himself there could be no foundation for it. There were even rumors, he added, about mountains actually higher than Everest, but he didn't himself give credit to them. 'I doubt if any peak in the Kuen-Luns is more than twenty-five thousand feet, if that,' he said. But he admitted that they had never been properly surveyed.