When the man called him, he obviously came to his senses and mentioned a mirage. Maybe the mirage they saw before was directly or indirectly caused by Shoggoth, in order to guide the prey back.
Introduction:
Dr William Dale, a geologist at the University of Stanik in Akam, recalled the story from the first-person perspective, hoping to prevent an important and famous Antarctic scientific expedition.
It tells how he led a group of scholars from Miskatonic University to explore the Antarctic, during which they discovered ancient sites and a series of mountains beyond the height of the Himalayas, as well as the evil behind them that was unknown to science.