Robert R.
Hotchkiss

A geologist is on an extended expedition in Antarctica (or as it was anciently known as Shalrodan) when he falls deep into a cavern system and discovers a remnant of a lost civilization called the Valrimir. He lives with them, works alongside them, and learns their language. And in the process he discovers the rich history of the Antarctic continent in the days before continental drift carried it to the bottom of the world...