I was a member of the Science Fiction Book Club when I was young and this was one of the selections. The story is riveting, and it's stuck with me for decades. In reading the reviews, many other readers have the same comment. It's haunting.
THE ICE PEOPLE by Rene Barjavel (and Charles Lam Markmann) is a Sci-Fi/Alternative History novel about an expedition to Antarctica that discovers a sphere buried in the ice. Buried in the ice...below the soil of the continent. They have to take a look at this! What they discover are two perfectly preserved humans--a male and a female--from a 900,000 year old civilization. The reader is taken back through time for a glimpse of this beautiful and exotic world through the stories of the female survivor.
This was a #1 Best-seller in France. I do have one warning. It has an ending that will shake you up. One you may never forget.